You might try holding your proposed SLR lenses in front of the G2 body in their approximate position to determine whether you can still see through the viewfinder. If they block too much of the view because of their size, you'll have to get an auxiliary finder to put in the hotshoe. They also must not block the rangefinder sensors.
IIUC, to use the adapter you manually set the focus based on what the rangefinder readout tells you, then compose and shoot. This is probably acceptably accurate if you're shooting stopped down somewhat. What I don't know is just how cumbersome the process might be, I've never spoken with anyone who owns the adapter.
In any case, enjoy your new G!
--Rick