Aside from disabling the internal bec, I usually add a capacitor to the main power leads. I just solder it to the back side of the board where the wires are soldered. A novak power cap usually does the job:
http://www3.towerhobbies.com/cgi-bin...?&I=LXKKN3&P=7
If you really want the MM to stay cool and have a super smooth startup, send it to Griffinru to do his stage 1 mod. He adds extra heatsink material inside the MM and mods the caps, among other things. I tested his modded mm back to back with a stock mm and his stayed much cooler and was much smoother too.