The weapon slot keys are defined in the .ini file in the [GameInfo] section.
Just change the text after "wep1=" to the key you want to use.
Edit:
Had forgotten to use curly snake for the wep keys which which caused the keys to be intercepted.
Fixed that now and you can use the same weapon swapping keys as you use in game, as it was intended.
Can u exactly show, what u meant in your last comment. I am having acertain error with the weapon swapping key part.