Simply search the value that controls the teamkill and freaze it, so tk's will not be counted. There are multiple ways of getting this.
1.Look at logs main exports and find something related to teamkill, then you can nop retn functions until you get something wierd, then you can dig deaper and find something that may control what who your killing. Maybe your teamkill count is server based but you can make a code cave and you may be able to "skip" the function that gets to hradba that your killing your teammates, and make it think that your killing your enimies.
2.Simply search in tsearch or artmoney unltil you find a value/offset related to this (may not work though, but worth a try
).
3.Get hradba functions and offsets by using a debugger and jmp them or make them "skip" (and no, you cant use TMK), so the teamkill count will skip or reset everytime you teamkill.
Take a look at my vietcong pawning movie, because it is possable.