I'm sure this one has been floating around for a while, but I just found out about it this weekend, thanks to LHoward's post on the TalkBass Forums.
It's a pdf version of Henry Portnoi's "Creative Double Bass Method", which I heard about years ago, but have never before seen. He starts the book with a section on bowing practice and styles, then moves on to "the fingerboard". Oh, and just what we need: yet another position-numbering system. He starts the player in what he calls "V" position (which would correspond to Simandl's "III" position), relying on the "tuning" harmonics to get the student in the right position.
This seems to be a very well thought-out and thorough method, and Portnoi seems to have gone to great pains to explain the "how" and "why" of all the technique very thoroughly.
To find the book, follow this link, click on "technique books" at the bottom of the page, then you can select the Portnoi book to download in .pdf format. I've already printed the whole thing out and will certainly be giving it a closer look (I don't think I can stand another trip through the Simandl at this point . . . )