Though I would chime in, since I went through this a few weeks ago.
I found that a 3 pound hammer and a long flat bat work great. I did it all alone, and was work, but did not kill me.
1. hammer 90 degree angle part of flat bar in between any two rivets. (get it in there real good)
2. steady your feet, and push the flat bar towards either side of the bus (window side) one or both rivets will pop.
3. move over two rivets, so that your flat bar is always being wedged between two well fastened rivets.
should cut your time way down...
PS: when you get to your last rivet, have a friend hold the sheet, it's likely going to fall hard, and if you are alone, you will likely crack a window or your face.
I cracked a window..