Yup, you can export from GE in the .kml format, then use GPSBabel to convert to .gpx format, which HBPC recognizes. Beware of significant offsets to the GE photo data - you may want to import your own photo overlay into GE, which works really well if you have access to better aerial photos than GE provides.
Edit: - Oops, I read that as Google Earth, rather than Maps. But I think my response might still be helpful.....both GE and GPSBabel are free downloads.