Which halve..........only joking... Iv,e been there many times, its damded hard work.
I use alloy wheel cleaner (try an area first & dilute if to agressive) ,let it dry some, go over with small wire brush on drill + small wire" toothbrush" style brush.
Wear gloves and a mask, Depending on how well you what the finish, keep going over with APC till you are happy with results.
Protect with ACF 50 (smells as it burns off) good luck!!