Help With Halo 3?

[\THE MAYOR//]

Can Someone help me with the Marathon Man Achievement? I need it to unlock the Security Shoulders. On This site cheatcc.com its says you can get it. In the campaign/meta game. If you can do it/help me heres my gamertag. Its exactly like this

CaPtAiN J13

Heres the Link..

http://www.cheatcc.com/xbox360/halo3cheatscodes.html

 

[Bagism]

http://www.youtube.com/watch?v=q3VCc5z3gX4

 

[monty c]

you need to find ALL 7 termanals