On a conventional flywheel, you can knock the ring gear off with a punch and hammer, no heat. Place the flywheel on a flat surface, lay the new ring on top and heat the ring with a torch until it slips on. You may have to give it a few taps with a hammer to fully seat it. I'd think an aluminum flywheel would be the same, but it'll probably take longer to heat the ring as the aluminum will suck the heat out pretty quick. It might be best to contact the manufacturer to be sure...