I just got my cabinet up and running today!

However, I can't seem to figure out how to adjust the settings in MAME so I can use my trackball.
Currently I'm using WinXP home edition with MAME 0.98b through MALA.
The trackball is plugged into the computer mouse port PS/2 so it should work just like a mouse. I know it works since I tested it on an older PC way back when that was running Win2000 and MAME32. I can't even get the mouse to work on trackball games at the moment.
Any guidance to getting me up and running with Centipede as soon as possible would be awesome! I'm dying to play it!@