MEK and Toluene (and acetone, to some extent) will dissolve the hypalon material (which is why the stuff is used in adhesives, to promote adhesive penetration into the material.)
But, for a quick wipe, it does work. I have used acetone as a cleaner on my old Achilles SIB(removing road tar and various marine oils and scums), and it worked quite well. Wet a rag with acetone, and wipe/scrub, allow to air dry before re-doing the same spot. Be damn sure you're not smoking while doing it, though.