You have multiple options with the Nanotubes...
1. Each of the three wheel mounting locations has all of the necessary holes to install a ToughBox Nano gearset. This means you can very easily install a motor to directly drive the center wheel (I would recommend it - that way if a chain fails, your "most important" wheel is still powered). This also means that you may do a 6-motor drive if you want to.
2. One of the Nanotubes comes with a set of spur gears to transfer power between one pair of wheels, and you can add chain to transfer power from the middle to the other end.
3. If you purchase one of
these (or the Hex equivalent), you can cut it to length and replace the standard axle. This allows you to use two sets of chain, as well as wider wheels if you desire, to create a more conventional all-three-wheels-connected-by-chain 6WD drive module. This is what we did in 2011, using 4" diameter, 2" wide IFI wheels with blue nitrile tread. Just note that you may need to think about chain tension in this configuration (we actually simply used high-quality #25 chain, and had spare runs ready to install in case of damage or stretch. Despite some HARD driving through two regionals and the Championship, the chain never stretched to an unacceptable level).