[T-Mobile Samsung Galaxy S 4] AlaskaLinuxUser:
Great! I am glad that you want to give AOKP a try! Here is my recommendation:

If you use Windows instructions

Go to: https://dl.twrp.me/jfltetmo/
and download 3.0.2-0 tar

Then, download this:
http://www.mediafire.com/download/7us5q44aab1xl9d/Odin304.zip

-Unzip Odin.
-Turn on your phone (normal turn on) boot up into the stock system.
-plug in your phone, let Windows find the drivers.
-Once Windows found your drivers, unplug the phone, turn your phone off.
-open Odin.exe
-Click on PDA, and choose the TWRP file you downloaded.
-With your phone unplugged and off, Now press and hold the DOWN volume button and the power button.
-When the phone vibrates, you can release the power button, but keep holding the down button.
-You will see a warning screen. Release the down button, and press the volume up button to enter "download" mode.
-Plug your phone into the computer.
-Press start/ok button on Odin.

You should see a blue bar on your phone screen that fills up from left to right. Odin should say "pass" or "success". Your phone should automatically reboot itself. If this did not happen, seek help. Seriously. :D

-Plug your phone into the computer again, and copy the Gapps and Rom from post #1 to your external sdcard of your phone.
-Now, turn off the phone again.
-Hold the UP volume button, and the power button.
-When the phone vibrates, you can release the power button, but keep holding the UP volume button.
-You will enter TWRP. Now you can release the UP volume button.
-You should now MAKE A BACKUP TO YOUR EXTERNAL SDCARD. -With this, you can always go back!
-After making a backup, you should wipe your phone. Select wipe, slide the slider to wipe your phone. This will not wipe your external sdcard.
-Install Rom.
-Wipe Cache and Davlik.
-Install Gapps. - Optional
-Reboot to system and enjoy!

If you use Linux instructions

Go to: https://dl.twrp.me/jfltetmo/
and download 3.0.2-0 img

and download this:
http://www.mediafire.com/download/6bbr7f9049uh338/m919.pit

Then,
$ sudo apt-get heimdall heimdall-frontend -y

$ sudo heimdall-frontend

-This will open up heimdall. Click the tab called "Flash"
-Under "pit" click browse.
-Choose the pit file you downloaded.
-Under partitions(files), click "add"
-Under Partition Details, click partition name, and click recovery.
-Under File (recovery.img), click browse.
-Choose the 3.0.2-0 img you downloaded.
-Click on the "Utilities" tab.
-With your phone unplugged and off, Now press and hold the DOWN volume button and the power button.
-When the phone vibrates, you can release the power button, but keep holding the down button.
-You will see a warning screen. Release the down button, and press the volume up button to enter "download" mode.
-Plug your phone into the computer.
-Under Detect Device, click "detect" - the Output box will say something like, detected.
-Click on the Flash tab.
-Under Session, click "start"

You should see a blue bar on your phone screen that fills up from left to right. Heimdall should say "pass" or "success". Your phone should automatically reboot itself. If this did not happen, seek help. Seriously. :D

-Plug your phone into the computer again, and copy the Gapps and Rom from post #1 to your external sdcard of your phone.
-Now, turn off the phone again.
-Hold the UP volume button, and the power button.
-When the phone vibrates, you can release the power button, but keep holding the UP volume button.
-You will enter TWRP. Now you can release the UP volume button.
-You should now MAKE A BACKUP TO YOUR EXTERNAL SDCARD. -With this, you can always go back!
-After making a backup, you should wipe your phone. Select wipe, slide the slider to wipe your phone. This will not wipe your external sdcard.
-Install Rom.
-Wipe Cache and Davlik.
-Install Gapps. - Optional
-Reboot to system and enjoy!

Let us know if you need more help! If anybody else sees an error here, then let us know so we can get these guys on the right path.