I haven't done a slider, but I have made a primitive DIY "glider" -- essentially a camera mount attached to sliding-door wheels rolling along a track. That proved much to bouncy for anything useful, though, so one of these days I will attempt my own slider.
Seems like a lot of work to me.... have you checked-out my DIY project? Takes about 30 minutes to build & you have a professional slider ready to go. http://www.indietalk.com/showthread.php?t=21716
Yes... with the feet. I still think you can get a better vertical movement out of a crane though. (IMO)
Check-out the galley page here: http://www.zazaslider.com/gallery.html
I made my DIY slider right around the time Zaza was starting out over on that "other" forum which shall remain nameless, I freely admit to stealing his design in great detail. This was more than a year ago, I just used it again on my most recent poptent spot, still rocks!