I have, and it works fine. Just assign different types of spells to different schools. The WORST thing you can do is try to translate Runequest into HarnMaster. Don't forget that Harn World was out for years before HarnMaster, and I personally think HM helped kill the popularity of the world. Everyone thinks you must play your games a certain way or they don't fit. Guess what, there's a TON of magic in the setting. If anything, Harnmaster is a poor fit for a ruleset to that world.
