Quick recap: The Panasonic AG-DVX100 is the only DV camera right now that shoots 23.976 FPS. Premiere Pro 1.5 is rushed out for users of this new camera, and not for anyone else. If you try to encode anything with an AVI (Video for Windows) profile, it will change the speed to 23.98 no matter what you do.
However, if you have a DV camera, you can cheat.
IN A DV PROFILE ONLY
I own a Sony DCR-TRV9, nowhere close to massive Panasonic. When my camera connects by firewire, I can preview video on it. I went into Premiere's Device Control Options and changed my camera's profile to the Panasonic AG-DVX100P. Check out the screen cap:

Premiere accepted the bogus stats. It sent a 23.976 rate to the camera and converted it to 29.97 fps, my camera's native frame rate. Next was exporting. I exported from an AVS into an uncompressed AVI and imported the new footage to check the stats. All over the program, the new footage came in as 23.976 fps. That's also in the screen cap. "Numb.avi" is the rendered file. So, I had a file that was truly 23.976 fps. No matter what resolution, interpretation or speed you gave the AVS, as long as you exported to 23.976, it accepted, thinking you were exporting footage from the Panasonic. This sounds good.
HOWEVER, you're running things through the DV profile. This has a list of disadvantages, mostly the fact that you can't change most of the settings, like resolution, and AVS scripts, filters, whatever, can't prevent the jagged lines you see below.

So, sorry folks. No flawless 23.976 fps unless you're editing in DV ONLY, with the footage captured in your DV cam. This is really, really stupid.