I don't think you can. Because of it's compact size, and I'm almost certain that the shifter is in the middle, it's only made for two buckets. I had a teacher that had one.
Word of advise: they were crappy cars. They were a poor attempt by GM to do what was called a mid-engine car (meaning the engine is in the middle of the car, with an actual trunk behind it, as opposed to a true rear engine car like the old VW Beetles or a Porsche 911.) If you really want something similar with the engine behind you, you may want to look at the Toyota MR-2.