well, mr. "iwillnotregistertoread", I can understand the answer you got after reading your rant on the other forum.
I'll bet you'd have actually gotten a "real" answer had you asked for help instead of saying that the "addon is pointless" because you can't get it to work.
Most of the people I know using Message Centre have no problems getting it to work at all. Understand, it is NOT multi-network capable, and will probably never be. Those of us not using mirc's multi-network capabilities have no problems at all with MC.
Like Collective told you, go to mIRC Options .. IRC .. Use Single Message Window