Ihave used Poly glue to sheet wings. It works well. You use the same as you would epoxy. The wood should be damp with glue but not wet. Sand and dust the cores well. I prefer vacuum bagging but with poly glue is slows the drying process and reduces the foaming. Not really an issue, you just have to laeve them in the bag for 24 hrs. I also don't glue the sheeting together, I tape them together and the glue will foam into the seam. Poly glue is very sandable so the seams are not visable under your covering. That being said, my preference is epoxy for sheeting wings. Mainly because I usually add fiberglass and/or CF reenforcements between the foam and sheeting, This can only be done with epoxy.