Finally got this working - turned into more of a project than I expected.
A while back I replaced my monsoon with the Kenwood 9140 - very nice unit.
But I wanted to make it mine and continue the theme, so I created the following image based on my avatar:

To get it installed was a pain.
It seems every Kenwood has a slightly different procedure to get to the config screen that allows you to set the "OEM Image".
For this unit it is:
1. hold down the "SRC" and "Volume down" buttons.
2. press the reset key with a paperclip (hole in lower left corner of unit's face).
3. install USB key with properly sized image (480x234)
4. once that completes it is not obvious, but you need to hit the reset again.
5. at this point the unit is still in standby, so go to the src screen and select the radio tuner.