Add a kit to a faction?

[Mr.Pfannenschmidt]

Hey folks,
I am trying to add an alternative sniper kit to the USMC-faction, but I don't know how to make it work.
I already created the us_sniper_alt.con and the us_sniper_alt_sp.con and added the entry to the spawners_us.con / spawners_us_sp.con

ObjectTemplate.create ObjectSpawner us_sp_us_sniper_alt_sp_preloadspawner
ObjectTemplate.activeSafe ObjectSpawner us_sp_us_sniper_alt_sp_preloadspawner
ObjectTemplate.isNotSaveable 1
ObjectTemplate.hasMobilePhysics 0
ObjectTemplate.setObjectTemplate 1 us_sniper_alt_sp
(to the spawners_us.con without the "sp", I hope that goes without saying...)

but when I right click in the kit selection at a supply crate it just gives me the normal kit.
What do I have to do? Which files to edit?
Thanks for your help!

P.S.: I am just a (german) coop player, editing this for himself... (I dont play MP)