Install needed packages
emerge gps5300driver gpsd
Configure /etc/conf.d/gpsd
GPS_DEV="/dev/pgps" RC_NEED="gps5300driver" GPSD_OPTS="-b -n -P /var/run/gpsd.pid -F /var/run/gpsd.sock"
Add startup scripts
rc-update add gps5300driver boot rc-update add gpsd default
Start /etc/init.d/gpsd and your GPS should begin working.
Not working yet
Read the gpsd man page for instructions on how to use it with ntpd
Discussion