Recording my experience here for those who may need it.
Take one Lifecam Studio, plug in.
You will notice that most apps recognise it, as it is a UVC webcam. Unfortunately, MS in their infinite wisdom decided to implement focus and exposure (and I think white balance) in software in the Windows driver. Yay.
Never mind - open source, as ever, to the rescue. The guy who built the CamHolder stand for the Lifecam also hacked up a setup app - it’s downloadable from https://github.com/downloads/HBehrens/CamHolderApp/CamHolderApp-0.2.b.zip and allows you to control focus and exposure. I suspect someone with more knowledge of the UVC protocol than me could persuade it to tweak balance as well.
After that, it’s just another webcam - BoinxTV recognises it, and it All Just Works.