Been looking, but no luck. I do have a KVC-23 sitting here in front of me, and the install manual says : "Note: Pin compatible with previous similar Kenwood mobile chargers".
Which means if you can find the cable for a KVC-23, or KVC-18, you could use that.
Unfortunately I haven't been able to find the service manual for it, and nothing I have shows a part number for the cable.
I also have a Motorola TDN9816A mobile charger sitting here (for the Jedi line of radios) and the connector is identical to the Kenwood charger. Likely made by a third party for both of them. Cable pinout appears to be the same.
So, looks like this is what you need:
Motorola APX Vehicle Charger Wiring Harness/plug Wpln4208 Nntn7624 Rln5233 for sale online | eBay