This DIY video shows a procedure used to carefully take a dent out of an alloy wheel. The dent was on the inside of the rim and the final result was not dependent upon any scratches or other blemishes in the rim. If that is a concern to you, you should use a heavy rubber mallet instead of a steel hammer. The rim did not crack, it is pretty near perfect shape and does not leak air anymore. Be safe and use gloves so you don't burn yourself on the hot rim.
2 years later owner reports tire balanced easily, does not abnormally wear tire, rides smooth and does not leak air.
Check my other videos: "DIY Breaking Stubborn tire bead off a rim using a 4,000LB press" "DIY Marathon of techniques to getting a tire to stop leaking against the bead"