If the wheels can all turn 360 degrees, then you only need them to turn in one direction. Just point them 180 degrees from 'front' and you've got reverse.
95 acutally produced a drive system something like what I think you mean for the 2003 season. All the wheels were inpendently steered and powered. Drills and Chips for drive, Globes and window motors for steering. The drive motors gearing was through worm gears. I've included a link to some pictures on 95's website. Anything in the picture gallery that is from 2003 may be of some use.
-Andy A.
95's photo page