Go here Combat Arms Hacks - MPGH - MultiPlayer Game Hacking
Scroll down until you find a working hack. One that doesn't have [patched] or [detected] next to it's name. I recommend you use http://www.mpgh.net/forum/164-combat...kick-more.html
Scroll down in that first post until you find the download, and then download it.
Extract the download with winrar until you have a .dll file.
Download this injector
Open that up as admin, set process to Engine.exe and click browse, find the hack .dll file you just got and click ok.
then start up combat arms.