would the switch light up when u switch on the spray?.. or it illuminates when parkers are on?
you wouldnt need to wire to acc... as u dont need it while car is not running. just run a live power feed /ignition and a ground of course.
your best bet is getting an auto IC spray & hobb switch in the long run. better alt is get the genuine manual spray switch.. as it only works at a push of a button .. bonus is not having to click on and off with a generic.
p.s. remember to put in a fuse!!! 