Can I use co-op on Halo 3 to earn the Guerrilla achievement?

[Tim J]

I've been trying to get it for a while. I keep getting killed by grenade happy grunts and I want to know if you can get the acheievement playing team scoring co-op.

 

[idontknowyou22]

well i did my achievements onlive with myfriends but i did team scoring but YOU have to get all the points not ur team so make sure u take everyones kill but if u want some points use the plasma pistol charge it up and hit someone with it and kill them and u get like 250 more points for useing the noob combo but i had to play the campian like 3times b4 i got my achements cuz i gess it didnt know that i beat the scoring for it