You can find CF EU hacks here: CrossFire Europe Hacks - MPGH - MultiPlayer Game Hacking
To use hacks, you need to download an injector. You can download then here: CrossFire Spammers, Injectors and Multi Tools - MPGH - MultiPlayer Game Hacking
Download a hack, then extract it. Do the same with your injector.
Open your injector, set the process to crossfire.exe, and set it to automatic inject.
Browse for the hack. Hacks usually come in .dll files. Look for where you extracted your hack. Double click the hack you want to attach.
After that, open up the crossfire Europe launcher. Open up crossfire Europe as usual.
After your hack will be injected. Close the injector after injector (or tick the option 'close after inject' if applicable on the injector).