How can I build a single instance application using Click Once?

I need to have a single instance application (as per this answer), but it needs to be deployed via click once.

The problem is that I require that click once doesn't automatically detect an update an attempt to load a newer version while the application is running. If it is running, then I need the other instance to be made active. Usually, when selecting a Click Once link, the very first thing it does is attempt to find an update. I want to intercept this and check for an already running instance prior to launching the normal update process.

Does anyone know how this is possible within a Click Once deployment scenario?