You guys are gonna love this one... but here goes:
I was visiting websites while waiting for people to post some threads on this and I had already found that thereisnomonkey thing.. So overjoyed with finally finding my problem I went to try it out.  Alas, the dreaded "This is cheat protected." message still plagued me and I've yet to get past it.
Here is my command line:
"C:Program FilesEA GAMESMOHAAMOHAA.exe" +set cheats 1 +set thereisnomonkey 1
So here is the really cool part... I figured maybe 3rd person was just being stupid, so I tried to activate any old cheat.  So I typed "dog" into my console and can you guess what happened?  I got a lovely message saying that cheats must be enabled on the server with the command +set cheats 1.
So what the heck... as you can see by my command line I obviously have the thing set.  So I guess there is something else to it.  Where exactly are you guys using the cheats?  I've tried to start a new game, I've tried to load a mission in the middle, I've start to start at beginnings of missions, nothing ever works... So what now guys, would love to hear your answers.. 
