which is easy to do as far as the microcontroller goes. ive written keyscanning algos before.
Heck if you had a dead Duo 210 or 230 black and white version, you could "possibly" fit an iPad or some other tablet inside the LCD housing, as a "slide in" type mechanism with a base docking connector on the other end that the tablet slides into.
Then the bottom half of the laptop contains an extended battery to keep the tablet charged, and the USB microcontroller that uses the mouse and keyboard.
That just may work, and is not hard to implement. You would need a USB AVR or a USB PIC type of microcontroller, and implement the HID stack. Heck there may even be example codes out there that does just this, and the reason i feel so is becuase of the MAME movement and custom interfaces for that.
Main PC: Intel core I7 920, MSI x58 platinum, Radeon4850
PB: tibook G4, ibook G4, Lombard, 160, 165, 180, Duo 2300x2, Duo 270c x2, 520cPPC, 3400c, 1400c
Desktop: G3AIO, 5260/100 x2, SE, SE/30, 512k, plus, LCIII, 7100, iMac G5 iSight, 6400/225