The G-connect page says it supports Time Machine backups so maybe you only need some of the steps described here to get the drive to show up:
http://code.stephenmorley.org/articl...network-drive/
Are you are able to connect to and mount the drive manually? If so, you should probably just need to do step 3c.
You can always use a different backup program like Carbon Copy Cloner and you get more control over space.