hell with elbow grease. mothers power balls are the cats-ass man just put it in ur drill chuck and go to town. available at your local auto parts store to. Mothers mag-alluminum polish is the best for any alluminum
It will take forever using elbow grease.
Use polishing compound and a buffing wheel in a portable drill.
Free how to buff & polish booklet, as well as polishing kits.
http://www.caswellplating.com/index.html
It depends how oxidized they are. If there's white crusty oxidation use some 220 grit sandpaper then steel wool. Then polish them up with Mothers mag and aluminum polish or NevrDull.