Not impossible at all.
I just did mine, and the hardest part by far was removing and reinstalling the bumper. I had 3 dents, and part of it was bent from the previous owner backing into something. Pounding out the dents and straightening the bend was fairly easy. I just laid the dent over a 2x4 and pounded/tapped away until it had all but disappeared, carefully working it out a little bit at a time. I used both a big heavy rubber mallet and a body hammer. I also used a 2x2 on end over the dent and bend, whacking it good with the rubber mallet.
Now it's not noticeable at all unless you know it's there. My local junkyard wanted $350 for a used one with smaller dents than what I had, so I really had nothing to lose by trying.