To keep the spokes from rusting I'd say it'll take at least 5-10minutes per spoke with a kitchen scouring pad then ACF50 which poses the next problem of applying using a brush so you don't spray the brakes!
Either way you'll all be happy to hear the end of it now, I've bought a pair of the 10 spokes cast wheels from a breakers yard for £350. Good nick, well balanced, no damage so pretty happy.
I'll be selling the XT rims on here soon, obviously my add will say how amazing they are!
Thanks blokes