not possible
you get whatever dpi you start with and that is it, you take (just as an example)
10 dpi and make it 20dpi it is going to be so badly pixelated you probably wont even be able to tell what it is, and you keep increasing it will only get worse.
example below from a Reds game I went to Thursday night 640x480 make it 1280x960 and see how it looks, this is only one size up.
http://www.boomspeed.com/montanaxvi/DSC00004.JPG
is 640
http://www.boomspeed.com/montanaxvi/DSC00004big.jpg
is 1280 i resized from the first one
you can still make out what everything is and it still looks somewhat ok, but with each scan then upsizing will make it break up more and more each time.
might wanna move this to the photo board, some of them guys might be able to help you out more or show a better example.