I just lettered a firetruck this same way last week. I used Oracal 951 black for the outline/drop shadow, Oracal 383 Ultraleaf for the gold, and Oracal 270F cast laminate over the top. Just set up registration marks for all of them. To locate the registration marks on the clear, I just use a pencil turned sideways and basically do a rubbing over them. I'm not sure how others do it, but it works for me.