I've had many people ask me how you use the "Custom Tunables" functionality in my program. I guess it would make sense to show you all how, huh? 

First thing you'll need is the tunables_processing script inside script.rpf. Load this file up in your favorite script decompiler (I like to use XBLToothPik's XSCToolbox).

To make searching easier, copy all the contents of the script and paste it in a text editor. Now you will search for your tunable. Thankfully, Rockstar was nice enough to store each tunable as plaintext. In this example, I will be using "TURN_SNOW_ON_OFF". 

Press CTRL + F and search for the tunable string:


You'll jump down to a PushString instruction with the tunable name. Since Rockstar's compiler is FIFO(?), the rest of the function call parameters are below it. The tunable index is always the GetImmediateP2 opcode just below the tunable string. Here's the structure of a tunable entry to make it easier (they are all like this):
getF 0
getF 1
PushString "TURN_SNOW_ON_OFF" <- Our tunable string
pGlobal3
GetImmediateP2 4694 <- Our tunable's index
iPush_1
Call @Label120

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With our index, we can now add it to my program as a custom tunable. Do something similar to this:



And there you have it! Pretty simple stuff once you get the hang of it. If you have any questions please feel free to ask and also if you find any cool ones you want to share you can post them, too. Please note that the beer hat and t-shirt tunables do not work anymore!

Credit to Tustin

sweet