response is a little dated, but hope the OP still cares

first of all, i hope the only reason you bought a turbo controller is because you suck so bad at the game that you have to resort to outside assistance

second of all, to answer your question (unlike every other douchebag that responded to this thread) treyarch has patched any ability to use turbo controllers online, the reason is that there were so many people who complained about people using turbo controllers for cod4 that they decided to add this nice little feature in the game

the patch works something like this: the turbo fire will only work approx. 100 shots per round. that means for the first 100 shots you fire with turbo engaged, you will have turbo fire. any subsequent shots will result in your gun firing 1 shot per second (which for some guns is VERY slow). anyway, hopefully by now you've already moved on