using the statusbar process viewer, the following command will allow you to start the GPS and log NMEA output to the external card (without running the actual map program):

sh -c '/usr/libexec/navicore-gpsd-helper >>/media/mmc1/gpslog.txt'

It is not timestamped, but can show the acquisition process.

You can watch it better in an xterm, but this lets me turn the GPS on for my old zmapper I ported from the zaurus.