hi, guys-
I did this on my G4 laptop. In DVD Studio Pro>Preferences click on Destinations. Click on the drop-down and change that to Palette Elements. Hit the "Choose" button and navigate to the external drive for each both Stock and Custom libraries (even if you don't have anything custom...it's cleaner). Select those and then "OK"-button your way out of the Preferences Pane.
It should remember this, even if you launch without the external drive. I accidentally launched DVD SP the other day without my external attached. It complained that it couldn't find the external drive, but it didn't reset itself to default, which is nice.
deb