I finally managed to borrow a BU-353 USB GPS receiver and added my very first roads to OSM. Here's my complete workflow:
1) gpsd -d ntrip://lindi:$PASSWORD@www.euref-ip.net:80/METS0 -f /dev/ttyUSB0 -N -n -D 1
2) echo rw | nc 2947 > a.dump
3) gpsbabel -i nmea -f a.dump -o gpx -F a.gpx
4) open a.gpx in josm, edit map, upload
Any idea how I could I apply DGPS corrections as a post-processing step? I don't always have access to internet.