On the dashboard view-but-soon-arrange-or-something page (with the edit/arrange/add panel links), add an "Install Dashboard" action.

This should pop a confirm dialog and then replace your homepage with the dashboard (maybe by writing to a user preference, I guess?).

If you replace your home page I don't think we need a way to go back to normal home, since Dashboards are pretty hidden. The confirmation dialog could warn you that you're stuck in the exciting new world of dashboards if you commit, I suppose.

Eventually this might have some options like "Install to: home page, profile page, project X, project Y, project Z...", although maybe those actions go somewehre else or something.