Guide for if you are using the DUALSHOCK®4 Wireless Controller to play GTA San Andreas on Steam. Connecting a DUALSHOCK 4 wireless controller to a Windows PC can be achieved via Bluetooth or a compatible Micro USB cable. Once you are in game, select Redefine Controls in the control-menu option and choose the own way to play.

However, unless you are using mods/scripts, the in-game controller settings are only 'partial' and would not function as played on the PlayStation (i.e. tapping X to swim fast). You would need to use a mod/script to map the keys to fully function. I also found out that the Touchpad and the Right Analog Button (R3) are the same input = JOY11, and that the input JOY 12 is missing.

CIRCLE = JOY1
CROSS = JOY2
SQUARE = JOY3
TRIANGLE = JOY 4
L1 = JOY5
L2 = JOY 7
R1 = JOY 6
R2 = JOY 8
SHARE BUTTON = JOY 9
LEFT ANALOG (L3) = JOY 10
RIGHT ANALOG (R3) & TOUCHPAD = JOY 11
??? = JOY 12 (MISSING?)
DPAD UP = JOY 13
DPAD RIGHT = JOY 14
DPAD DOWN = JOY 15
DPAD LEFT = JOY 16