Actually, the aluminium is screwed on I believe, and mostly just held in place by the other parts and a hooked lip. I'm going off of memory, but I do know that there are no rivets holding on the aluminium. the only rivets involved are those for the fender flares or inside wheel well area.
I had to take the aluminium off of the first side I had installed because I forgot to place the foam pad under it. So i did the uninstall of the sidestep that I was working on and put it in. it wasn't fun, but nothing too difficult if you have the time and drive to do it. Then just taking the aluminium pieces (2 of them) to a powder coat company would be all you need to do.
Good luck and post pics if you do it.
Happy New Year!