Try Todd Johnson's stuff:
http://www.toddjohnsonmusic.com/store.php
The "Fishin' for Grips" one is chordally-oriented, so that should help. And keep in mind that, while fingerboard knowledge on a 6-string is its own thing, learning chordal and scalar shapes on 4- and 5-string basses does transfer to 6. As long as you are using BEADGC, of course. The fourths tuning makes all scale and chord shapes transferable to other strings, of course.