If you can get some shavings from say a deck opening, then that's the ideal - the chemical composition will be identical.
Clean the area up with some metho, and leave it to evaporate off.
Get a blow torch and a paint scraper; heat the paint scraper up (and keep it warm) and you then melt the shavings into the hole using the scraper to pull them into the hole (not the blow torch)
Hope that helps a bit; it's the technique I've used on PE canoes in the past.