Go For it
I was faced with dying some arm rests from red to saddle, so as a test i died some red vinyl with SEM. then i made a stool top for the shop out of it. after a year of everyone's butt sitting on it, there is still no trace of red. also i didn't do so much as wash it befor dying it. something i don't recommend. the stuffs unreal.
However, i used the same product on a Rod Doors headliner for a truck (Cycolac, i think, or ABS), and the constant rubbing of the sun visors rubbing on it rubbed through.