What kind of Ajax was it. They make a liquid dish soap. I'd put the pants in the washer and wash them like usual. For the car rent a carpet cleaner and use that, skip the detergent.
If it's the powder kind used to clean sinks or bathtubs. Just brush it off of you and vacuum your car, I think it's activated by water so you don't really have to worry about it bleaching any thing. If it gets wet just follow the directions for the liquid dish soap.
