How do I modify Motion control scripts?

[UnsealedWings]

I'd like to edit the source code, and potentially change how the left and right hand interact with a gun.

Basically, I noticed in RE7 that Ethan let's go of the handgun when holding left grip but not right grip, after about 3 seconds he let's go.

However, RE2 and 3, you can't hold anything with both hands unless aim mode is enables (Which makes you walk slow).

So how would I go about changing those things, or just getting to the file that has the what I need to start on it, what's it called and where in the source code is it?