John,
I had success putting on the overlays with white glue on the bare plywood. Then I coated the overlays and surrounding area with epoxy to "smooth out" the overlay edges. Once I had a nice smooth transition from the overlay to the plywood, I proceed to epoxy and glass the boat "as normal" . I did pre-coat prior to applying the fiberglass (but please let's not get into the debate on the value of pre-coating again.).
This may not be the best way but it worked for me.
John VB

PS the Veneer I used did not have a paper backing so I put the glue on it, allowed the glue to almost dry, then I used an iron to apply the overlay pieces. The heat from the iron reactivated the glue. Again there are lots of techniques this is the one that worked for me