MarkFleming, (GoNorthWest) has jest release a map set for garmin GPSr that cover the SW trails.
Quoted from the mailing list:
I would very much appreciate people at least checking out the web page and providing constructive feedback. This project is in it's infancy, and there is lots of work to be done. But, in my own field testing, it's proven to work pretty well so far. I intend to allow user contributions in the very near future, so you can send me new trails or corrections to current trails. Anything that makes it better!"