Warning: Please follow these instructions at your own risk. I am not responsible for any damage or information loss that could result from following this guide. Also, note that installing OS X on PC is illegal. Please buy a real Mac if you're satisfied with your Hackintosh. This guide is for evaluation purposes only.

Requirements

An Intel-based PC with UEFI bios
A USB flash drive with at least 16GB capacity
A dedicated hard drive (SSD highly recommended)
A computer running OS X (10.9 or later) for preparing the installation USB flash drive

I chose to avoid the UniBeast installer (by Tonymacx86) because of its commercialized nature, as described here. Here is a vanilla guide to installing El Capitan on your PC!

IIRC the version of X11 bundled with Wineskin is broken in El Capitan. So go into the Wineskin app (right click on the app and show package contents). Then open the Wineskin app in that folder. When it opens click advanced, then options, then check the last box. (force use of system installed XQuartz). IIRC the version of X11 bundled with Wineskin is broken in El Capitan. So go into the Wineskin app (right click on the app and show package contents). Then open the Wineskin app in that folder. When it opens click advanced, then options, then check the last box. (force use of system installed XQuartz).

Preparing the USB Installation Drive

First things first. We need to prepare a USB thumb drive that will contain the installation files as well as the bootloader and custom kexts for our specific Hackintosh build.

Download El Capitan from the Mac App Store

Head over to your existing OS X environment running 10.9 or later and open the Mac App Store.

Search for 'El Capitan' and click Download. The download is completely free if you're running OS X 10.9+.

Wait for the download to finish (this could take some time).

Format the USB Drive

Open Disk Utility in Applications/Utilities and locate your USB device. Make sure you've backed up anything important on that drive as it will be erased forever.

Select it, and then on the right, click the partition tab.

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Click Curent Layout and change it to 1 Partition.
Set the Name to USB.
Set the Format to Mac OS Extended (Journaled).
Click Options and select GUID Partition Table.

Click Apply to format the drive.

Copy the Installation Files to the USB Drive

Now that we've downloaded the installation files from the Mac App Store and formatted our USB drive, let's copy the installation files to it.

Run the following command in the Terminal (Applications/Utilities):

The command will run a script inside the Install OS X El Capitan application that will copy the installation files to the USB drive.

This process takes about 15 minutes. Go out for a quick run, or a hamburger, or both. When you come back, it should have finished.

Installing a Bootloader

If you tried to boot from the USB drive as is after the previous step on a PC, it wouldn't work. We need a bootloader that makes it possible to boot OS X on x86 and x86_64 PCs.

There are 3 popular bootloaders to choose from.

Clover
Chameleon
Chimera

I went with Clover as it seems to be the most popular choice among other El Capitan installers, mostly for the following reasons:

Clover is an open-source EFI-based bootloader created on Apr 4, 2011. It has a totally different approach from Chameleon and Chimera. It can emulate the EFI portion present on real Macs and boot the OS from there instead of using the regular legacy BIOS approach used by Chameleon and Chimera. For many, Clover is considered the next-gen bootloader and soon it will become the only choice since BIOS in being replaced by UEFI in every new motherboard. One big feature of Clover is that iMessage, iCloud, the Mac App Store works along with Find My Mac, Back To My Mac and FileVault since Clover can use the EFI partition. (Read more)

Install Clover on Your USB Drive

Installing Clover on your USB drive is relatively easy. It involves running an installation wizard and selecting some options.

Download the latest Clover installer from here.

Run the installer.
Click Continue twice.
Click Change Install Location and set it to your formatted USB drive.
Click Customize and check the following options:
- [x] Install for UEFI booting only
- [x] Install Clover in the ESP
- [ ] Drivers64UEFI
  - [x] OsxAptioFixDrv-64 - fixes memory map created by AMI Aptio EFI. Booting OS X is impossible otherwise.

Click Install and wait for the installation to finish. It shouldn't take more than a minute.

Copy Essential Kexts to the USB Drive

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Next, we'll need to copy some kexts (kernal extensions, similar to drivers on Windows) to the USB drive.

FakeSMC.kext - open source SMC device driver/emulator developed by netkas. Tricks OS X into thinking it's installed on Apple hardware. Absolutely required for Hackintosh installation.
NullCPUPowerManagement.kext - disables AppleIntelCPUPowerManagement.kext which may cause kernel panics when you try to boot from the USB drive. It's optional, copy it only if you get an AppleIntelCPUPowerManagement-related kernel panic.
ApplePS2Controller.kext and AppleACPIPS2Nub.kext - adds support for PS2 devices (such as PS2 keyboard/mouse). They're optional, copy them only if you still use PS2 devices.

Download these files from here and copy them to the EFI mounted volume at /EFI/Clover/kexts/10.11/.

Now that the installation USB drive is ready, let's install OS X El Capitan!

Boot from the USB Drive

Restart your computer and boot from the USB drive (Press Esc/F8/Del to access the boot selection menu).

Use the arrow keys to select Boot OS X Install from Install OS X El Capitan (It should be selected by default). Press the spacebar and select Boot Mac OS X in verbose mode. Verbose mode means that you'll be able to see exactly what's going on under the hood as OS X attempts to boot up its installer. You'll be able to see the exact error message if booting fails.

Press Enter and cross your fingers. Clover will now boot the installer from your USB drive. This could take some time, in my case, it takes around 5 minutes (Don't worry -- the startup time is around 5 seconds after installing on an SSD).

Did it fail?

It's more than likely that the boot will fail. Don't panic (ha-ha), as kernel panics usually mean that you forgot to copy an essential kext to the EFI partition. Look up the exact error you're getting before the boot log comes to an end and search Google for a solution.

Once you find an additional kext that your system needs, you'd attempt to copy it to the EFI volume, only to discover that it's gone! Not to worry, it's just unmounted and hidden. Follow this guide to mount the hidden partition, and then, follow the Copy Essential Kexts section above to copy it to the USB drive's EFI partition.

Format the Target Hard Drive

Once the installation wizard boots, the next step is to prepare the hard drive that you want to install OS X on.

Click Continue, followed by Disk Utility.

Select the target drive to install to (not the USB drive!) and click the Erase button. Make sure to back up anything important on that drive, as it will be deleted forever.

Set the Name to El Capitan.
Set the Format to OS X Extended (Journaled)