Hey Greg,
I just received my D70 last week. What a beautiful machine!
I don't have the Scopetronix adapter, but I'm seriously considering it. So far I have used the D70 on one clear night at prime focus and with my limited experimentation I suggest the following:
1. It seems like the Camera always does some processing to the image even when you select a raw file format. To get a true raw file you have to set it to raw, set it to automatically create a dark frame and turn off the camera as it's creating the dark frame (it shoots your first shot and then starts to create the dark frame). Powering it off when it is creating the dark frame will save the original image you took without doing any processing as it's trying to save your work before it shuts down. See http://astrosurf.com/buil/d70v10d/eval.htm for more information.
I'm experimenting with Capture 4 (Nikon's software to control the camera, and there is an option that may allow for a proper Raw file.
2. Use the remote (it's quite inexpensive), but don't forget to change the timeout setting on how long before the remote setting reverts back to single shot mode. Use the remote even if you are controlling the camera via a PC (Capture 4). It appears you cannot shoot from the PC in bulb mode - hence the need for the remote.
3. Take some Raw image shots with the lens cap on at different exposure times so you can subtract these noise images from the true image. I found that my D70 has a bit of a glow at the upper right of each image (that would be bottom left of the CCD, I think) especially noticable when you get into the 5+ minute exposure length.
4. For focusing I'm using a mask that has two holes in it and that covers the telescope opening. I aim at a fairly bright star. When out of focus you will see the star as a double. Focus until the image forms one star. Test the focus by taking a shot of the star and viewing it on a laptop. Refocus as necessary and then lock the focus knob.
5. I use Photoshop 6.0 and Registax2. Lot's of experimentation required here... but here are my first two shots using the D70:

- about 7 frames at various exposures (average of about 1/1250th of a second) and stacked and processed.

- about 5 frames at various exposures (average of about 2 minutes each) stacked and processed. The guiding on some of the frames wasn't the greatest, but I'm still practicing.
The sky was moonlit, seeing was poor and I was in a fairly light polluted area. No filters were used.
Cheers,
Paul Mikulecky
Lost Pencil Animation Studios Inc.
http://www.lostpencil.com
"The art of character animation is to try
to catch lightning in a bottle.... one volt
at a time." Brad Bird