Hi,
I do not have a definite answer on this, but I believe the current version still doesn't support click once. I have discussed deployment issues a couple of times, including the lack of a runtime redist installer, and have been told that at present the only supported way of installing Pos .Net is to use the SDK. Yes, that's right, you have to ship the SDK to your users and then during the install say to just install the runtime !
Given that, I don't think click once is supported.