CuteMouse does the trick, Thanks.
It even allows me to be able to have only one device on at a time, so that moving the spinner during a track ball game doesn't do anything.
I did run into one issue though, GaeLauncher is not happy when the regular mouse.sys is not loaded. It would lock up the whole machine when I hit escape or tried to start a game.
So for now I am running with mouse.sys for the PS/2 device. For game that require the spinner, I just added "ctmouse /S1" to the .bat file that launches them. At the end of the .bat I have "ctmouse /u". This way ctmouse take over and the game sees the serial spinner, then after the game it unloads itself and mouse.sys regains control.