~5 years ago when I first got some DDR pads I was doing stuff like this. I was surprised I didn't lose by more in NBA Live to my controlling-using brother... but of course I must give the most credit to the computer-controlled portion of the team.
The two non-pad-designed games that worked best would probably be Bust A Groove and Um Jammer Lammy. Moreso the first. For Lammy, it was more a case of setting it on easy mode, so you could just run/mash two buttons. With no L/R on the pad, any other way would be trouble.