You must have CLEO for GTA 3 (can be found here) Extract to the GTA 3 dir/CLEO folder.
In version 1.0 (Slow Motion Mod) press CAPS button to activate/deactivate
In version 2.0 (Focus Mode Mod) press FIRE button to activate, and in 2 seconds it will deactivate on its own.
You need to download version 1.0 to get the required american.gxt, or version 2.0 will not work.
ATTENTION! Will replace your american.gxt. If you have my speedometer mod already, then this is okay, because this american.gxt will work with it. If you don't have my speedometer mod yet, and you wish to add it, then don't replace this american.gxt with the one in the speedometer mod.