I mapped out the display and keypad today, which was enough to get the 20B hex 4 banger project ported and running. No power management at all, yet.
I'm still fiddling with the LCD settings, but so far, so good.
My biggest failure was the debug UART--I simply couldn't get it to transmit. Ended up turning the CPU clock rate way up and bit-banging a 9600 baud output, which allowed me to decipher the display and keypad. (Probably something dumb that I forgot to configure, but it doesn't really matter now.)
Now for the tough parts...