I've never done any smoking or low-temp stuff on a 3-wheeler. When I've smoked stuff on a one-touch, I cover over two of the vents with that adhesive tape for metal ductwork (not the 'duct tape', but the silver stuff with the adhesive backing that you peel off). It gives a good measure of air control, and comes right off without leaving any residue. I set it up so the fire is right above the open vent, so that I can sweep ashes as I go.
I used to dream of getting a 3-wheeler as a dedicated smoker, but then I found a sweet used WSM and now I think I'll stick with the one-touch for my kettles. It is just so much easier to clean and control.
I also like to mark out some index marks on the one-touch housing to designate full-open, closed, and half-open of the vent. This makes it much easier to choke down the fire after lifting the lid, or to stoke up the fire before leveling it off to the previous level of air.
Photos here:
http://mikestavlund.com/2012/01/grill-hacks/