It'll keep paint from permanently sticking to the spoke or nipple..
It will be a serious pain, depending on how bad the rims need painting or if they need any body work to fill pits, etc, you might go crazy by the time you finish.
It will be so much easier to refinish the rim apart and get a proper job. If you have access to some sort of media blaster that can strip the old finish off without ruining any spoke plating, etc, you might find that would make it bearable. Otherwise you might wear off you fingerprints before you finish. You are going to tend to pull the new paint off the rims when you strip your masking off the nipples so even that part of it will be a nightmare.
Respoking is not that hard. I did my first set on my Roadmaster project......and they came out pretty decent, and look perfect. I looked at every youtube video I could and asked questions.....and got shiny new spokes and nipples to boot. No, they are not within .0000001 but they don't have to be on a cruiser.