Ok, here are some easy steps
1st- Go online SFDM
2nd- Enable code
3rd(optional)- Edit code value to your likings (edit stats)
4th-Play a full RANKED game(can be DM, TDM, OBJ, anything..)
5th-When game is finished, log out and shut your psp all the way off (so when you turn it on your psp restarts)
6th- Log on your account
7th- Enjoy being kicked from games because you are a hacker
P.S.
If the code doesnt work, try restarting your psp until it does. it should work