Bill of goods for converting 2xN900s:
-2x mugen battery covers, search ebay for extended battery cover N900 not listed as mugen
-2x 450mA USB charger for e-cigarette battery (thanks dr frost dk) to rip battery manager board from
-4x blue scud battery, to make two 3000mA/h double battery packs
-2x Palm Pre cylinder wall wart AC to USB, this is what the base needs and they are now pretty reasonable on ebay/amazon
-2x Palm Touchstone bases, they pretty much require the real palm charger above, the N900 charger is a no go so might as well buy the real deal than save a $2-3 on an incompatible power supply
-2x Palm Pre Touchstone backs, to harvest the coil and circuit board
-Hobby brass, will snip to the right shape to make contacts between door and N900/harvested charge regulator soldered to N900 battery +- poles.

I have one Mugen N900 door with the Palm/Touchstone coil installed, the sticky holding the coil is weak, I might try cleaning the next one with alcohol before sticking the coil down. The magnet is just strong enough to hold the phone down to the charge pedestal. Will see what works when the other touchstone door, batteries, regulators, and Palm wall chargers arrive.