I used spray can's to repaint the factory body kit for my Cutlass Ciera, I got the kit from a dark red International Series Ciera. It was a lot of work but it can be done. It helped that the Ciera bumpers were more semi-gloss than high gloss like the Alero has. Hopefully this gives you an idea what a spray can will get you. I wish I had better pictures but the digital cameras 15+ years ago sucked..
ignore the nasty bondo job lol.