Increasing ISO in RAW

If one shoots in RAW, isn't it possible to change the ISO post capture? So if I took an ISO 200 15 sec image, when processing the RAW can I change the ISO to 3200 the way you can change white balance? If I took an image of a star field, would this enable me to capture more stars than in the original image? As many as if I had taken an ISO 3200 15 sec image in the first place?

FYI the reason I need to do this is that the camera I want to use has an artificial ISO-shutter speed limit.....that is, the limits are ISO 100, 30 sec - ISO 200, 15 sec - ISO 400, 8 sec - ISO 800, 4 sec - ISO 1600, 2 sec - ISO 3200, 1 sec.

So this would be a way around that limit.

http://www.dpreview.com/forums/thread/3136547