You should look in the Metal Gear cosplay thread, which is located in this forum as well - I think I've heard people use some sort of body suits but I 've never really looked into what goes into creating MGS4 Raiden, as I've never really been interested in cosplaying him ;^^
Good luck on your costume!
Major Ocelot - Metal Gear Solid 3 | Revolver Ocelot - Metal Gear Solid | RED fem!Spy - Team Fortress 2 | Footie Pajama Commander Shepard - Mass Effect
Cosplay in Progress
Leonardo Da Vinci - Assassins Creed 2 | Major Ocelot(Revamp) - Metal Gear Solid 3
Braig - Kingdom Hearts | Sheik - LoZ (Brawl version)
Colonel Mustard - Clue board game | The Boss - Metal Gear Solid 3 | Xigbar (Normal & Tweedle Dee) - Kingdom Hearts