I just looked at Dale Titus's article about buying and playing the fretless electric bass on the Warwick site and I had a thought. What I've noticed, in general, about learning to play the fretless (or the electric bass in general) is the lack of method books that take the student logically and progressively up and down the neck. If you look at our orchestral cousins (Simandl Books I and II in our case is the classic bass example), you'll see methods that induce the student to eventually learn to put his/her fingers down at the correct location. I'm not aware of any similar text in the electric bass field.

Steve Bailey had a good book that I worked through, back in '93. It was fairly straightforward, going through all the intervals and such, and then there were a few challenging etudes. I'm not sure wether it's still in print or not.

I'm familiar with this book. It's OK, but it's still not IMHO a cogent thorough methodology.

Not only the book is still available, there's also a 90min video. The video is not really like the book but it shows some helpful things in shifting and one-finger-per-fret methods.