If you have the room just plant typical seedlings. Be sure to get shore pine from Pacific Slope seed sources and not lodgepole pine from the Intermountain Region. Up my way there are native shore pines that do, in fact grow in wetlands that flood during the winter, drain during the summer. At my instigation a friend and I canoed into an island east of Everett one year to walk among native wetland shore pines there, the high water mark on the trunks was above our heads. If you Google for pictures of Ebey Island and look around a bit you should be able to see some of them, there are several stands there - where it grows mixed with Sitka spruce, another characteristic wetland tree in the Puget Trough.

I also once read on the internet a serious (as in Forest Service) account that said this representation in the bogs and swamps here was actually from the Alaskan population and not the same race as those out at the beach. When I looked for it later I couldn't find it, and I have never seen that assertion made anywhere else.