How to get manual focus Nikon 105 VR lens in Nexus housing

Hi, I'm buying the Nexus housing for my Nikon D200 camera and 105mm VR lens. I'm hearing that there's no focus switch knob s.m.c. on this housing.

Is there any other way to get the camera to focus manually or at least keep the focus once it's done so the lens doesn't keep going back and forth all the time in low light conditions?

Any ideas are welcome!

Thanks, Erika.

Contributed by Erika Antoniazzo added 2007-07-30