I'm exhausted, so I'm not sure what I was babbling about earlier, or now for that matter, but here's the link:

USB <- OR -> TTL Seria Adapter Threadl

PL2303HX USB to TTL Converter Module

Since my brain is firing on just three of eleven badly tuned cylinders ATM:

How about just skipping all the wiring mess and converting Bluetooth KBD/Mouse Protocols to an ADB pigtailed receiver box? )