On MassChaos All GM server (3.3.3) The level cap is 80 (even for the admins)
I discovered that if you set your level using .mod level -1 setting your level to -1. you will get a WoW error and it will kick you off the server.....
however, upon logging back in it will bug out and your character will be level 255. you will remain level 255 untill an admin sets you back down to 80!
Normal GMs dont have the authority to take u to -1... but admins do.. there is plenty of donor admins who would be happy to do it for u... or what I did is just said "hey mate, put me to -1 level and see if it works" he was like "lol ok" and then it DCd me and when I logged back in I was 255
Enjoy!