in the root-folder of the sd-card, you find all GPX-files (tracks per day), saved by the garmin-device.
very cool site to create img-files is http://garmin.openstreetmap.nl/
i tried it with my GPSMAP 60CSX and it word (very) fine!!
** ** WARNING ON MAC ** **
after editing the img file(s) on the sd-card be sure there are no .Trash-Folder(s) etc. on the card. these folders result in carshing of the 60CSX!!!
rm -R .S*
rm -R .T*
rm -R .f*
to combine old maps (eg NT Europe, TOPO…) do the following.
Start the GMapTool (Only windows 😦
Select/add the file with the OSM data (eg gmapsuppOSM.img) and the file with your MapSource-data (eg gmapsuppTOPONT.img)
On the combine-tab choose your outputfile (eg gmapsupp.img) and press combine all.
then copy the outputfile to your garmins sd-card (/garmin/) and be happy!