I once wrote a python script that translated my waypoints into a .osm file that could be opened by JOSM.They were placed in a separate layer. I copied the nodes over to the “main” layer and then uploaded the file. Of course during the copy process I checked whether the items did not exist in OSM yet.

The conversion program also worked for e.g. housenumbers.

I wrote about that on my diary in 2013.: http://www.openstreetmap.org/user/escada/diary/19675