Zandronum

Can somebody tell me, how to make rank system, that work like this:
You kill enemy, get item XP (A_GiveToTarget) Then when you got 500 XP your class changes. And also, how can I make classes that work like this? And are NOT choosable from menu.

BTW does anyone have STG44 or Venom Sprites?

Hm, RGA 2/3 (Whatever i don't like it) uses a system like that, make the item as inventory, like flares, (WDI) then make the XP go to the rank system. I just don't give you the code because i'm not good at ACS (To be honest, i don't understand it all but meh...) and sorry, i dont have STG44 or Venom Sprites D;.