KeyShot is a nifty 3D renderer and animation software. Unfortunately, video output was an afterthought by its makers, and I am unable to output an AVI at 1920 x 1080 frame..... I am left with 1920 x 1081.

Without getting into the why's and workarounds.... is there any way to have Premiere (CS6 in my case) to import a 1920 x 1081 clip?

The import seems to work fine, but the clip is black.

And so you understand, I have already attempted to resize (using TMPGenc), but the resultant clip has stuttering problems (another issue that is making me lose my mind). The AVI (uncompressed) from KeyShot plays smooth as butter with Media Player Classic.

Any ideas?

Taking a real flyer on this as I have no way to test it, maybe re-coding the avi with a different codec would straighten it out. There are lots of conversion programs (I use one called Brorsoft Ultimate, but there are any number of them). Perhaps you could post a few seconds of the unaltered clip for testing?
I realize you tried to re-size the clip, I'm talking about just converting it altogether to a different codec.

Premiere will import nearly any resolution but If its black you are missing the codec.
Or its using a codec that Premiere does not like such as e.g. dvix.
Use Mediainfo to determine the codec.