Did you look at their Web site? The installation instructions suggest using two positions of a three-speed (presumably MTB) trigger shifter, and the review by The Hub says they used "an old Sturmey-Archer trigger shifter. The Bicycle Times article states "Shift actuation is performed by any indexed or friction front shifter, so compatibility is open to just about anything from integrated road shifters to thumb shifters." So it sounds like it is not too picky.

If you go the trigger shifter route I would suggest that you use the second and third gear positions rather than the first and second as suggested in the instructions; this will prevent you trying to force a shift past the internal stop, which is cautioned against. If you need to use a friction shifter just make sure that you adjust it so that it is adjusted to pull enough cable to shift it solidly into gear and no more; then you will not be able to pull the cable against the stop. Install a barrel adjuster for fine adjustment if one is not present.

Edit: They are also pretty adamant as to the need to have the BB faced to exactly 68mm and strictly parallel for best bearing performance (and life I expect).