Wow! Nice find! Should work fine with any 2 1/4 trackball. I bought a clear "sparkle" cue ball from these folks for my Kensington Turbo Mouse hack and used some red LEDs to illuminate it:
http://www.paramountindustriesinc.com/prod_5bllrd_5bal.asp They were sloooow to ship, and charged the same price as the cue ball to ship it... Results are good however: