Did more searching and finally found the answer on the Adobe forums.
To quote:
Create a custom Keyboard setting in Pr.
Click on the “Go” command in the Finder command bar, hold down the “alt” key while the drop-down window is open, this will reveal a hidden “Library” option.
This is not the same Library as the one in which I have been searching for my .kys files! This is another Library, a different one, a mystery Library … OK it’s the user Library, I’ve been looking in the System Library the whole time.
There it is under:
Application Support/Adobe/Premiere Pro/6.0/my.kys
So there you go.
Jeff K.