I've also got the U-Trak and love it. It was painless to mount on my MDF control panel, and on the net there's is a very nice step by step instruction (with pics) that somebody put together on how to install it. I don't have the link, but it should be easy enough to find if you look for it.
I'm assuming the X-Arcade unit is the same one they put in the Tank Stick. If so, it's worth noting that my brother has been using an X-Arcade Tank Stick for 3 years now and, while he is generally happy with it, whenever he plays on my cabinet he says "Man, I like your trackball SOOOOO much better than mine."