you can easily convert it to a stepmania machine if the seller did not fuck around with the wires to much. It should be pretty easy, you can check the DDR Simulation forum for a how to.
I saw that machine on ebay... I think only the pads are official, the actual cabinet is a knock off that someone built (or at least thats what it looks like).
Also I dont think those are even the arcade pads. Just a heads up, beware if you are interested in that machine.
if anyone is interested this is what he is talking about...
DANCE DANCE REVOLUTION 8TH MIX EXTREME ARCADE GAME - eBay (item 310054312648 end time Jun-03-08 16:53:27 PDT)