Thought I'd update everyone on my progress...
I'm nowhere close on issuing different payloads dependent on key-presses. And I admit I've been slack on the keyboard mapping support - Sorry!
Instead I've been concentrating on Mass Storage Support
Got the Ducky this morning to act as a Mass Storage Device on Windows and Linux.
Will update the code, and release some source later today, after some more testing.
Please be patient, and await more news later today.