all you need to do this is to have a internet cable plugged in to your computer. you can not do this with wireless computers.
step 1. join any game you want.
step 2. find a hiding spot and go there.
step 3. unplug your internet cable and since the people are frozen go around and kill them. NOTE: if they find you and kill you while your tapping then it won't work and you won't get the kill.
step 4. after killing people plug back in your internet cable (do not leave it unplugged for too long otherwise the server connection will end and combat arms will shut down.
step 5. enjoy tapping!
''That Was Easy'', lol sound similar to an office material supplier's commercial?