First, ditch the BBs :P Buy BB Bastard. Like said by Latency, use at least .20, .25 if you can.
I'm not familliar with the MEU, but I have an Hicapa, so it should be pretty much the same.
Remove the slide by pulling it until the small notch, before where the slide would normally catch. Push on the slide catch from the other side of you gun and it should fall down. Remove the slide by the front.
You should see a small adjustment wheel. Tune up or Down.
EDIT : Just found this :
http://www.facepunch.com/threads/868...911-MEU-Review
Might be a good read.