The Honda one used a variable cam based system, where the cams pumped lifters which provided turning force on an eccentric flywheel. This flywheel was designed to suppress the "surging" motion the lifters created. This flywheel was connected directly to the front-side chain cog. The cranks were connected to the gear-drive which rotated the cams.

DOwnside to this mechanism is if it is rotated backwards, it destorys the transmission...so the cranks have their won freewheel, and I think the front drive cog was on a special freewheel, to prevent any chance of counter-rotation of the machanism.

How shifting was done on it, was the cams could be moved in a fasion similar to VW's VVTI, so a lower gear would have less cam lift, while a higher gear would have more cam lift. What the friction twist-grip shifter did was control the position of the cams, in a similar fashion as a shifter does a deraileur.

Pretty much that was all I remember from the MTBA article...and yes, I drool about that bike everyday.