This is because when they made this useless add on to AA they tied all 3 games together, so most of the game gets it's information from Allied Assault and Spearhead. That pk3 I posted only works if the server.exec isn't running, after setting up a proper server and re testing I see it doesn't work. This is way there never has been many BT servers around, never was and never will be, there is no "easy" way to do what you want. Maybe Forsight or MOHCI program can do it. Back when TMT was still up and running you can find a answer, I read a post about secondary weapons on it and how you had to jump through hoops to change how they worked. 99% of people mod Allied Assault because it's less complicated. Ther is a post here some place with a Archive link to it maybe something is still up.
Sorry I can't help, not as smart as some of these guys are.