Us fling-wingers don't have an appendage free to work a whizz-wheel in flight...
Our VMC minima are lower than yours so I've not yet had to divert anywhere. (touch wood).
As someone else has already suggested - just select the 'nearest airport' function and pick one (on the Lowrance Airmap you just hit two buttons together and it automatically selects the nearest airport for you). Then all you have to do (aside from watching your airspaces on your map) is keep the heading it tells you that you need, the same as the track it says that your making.
I like the star idea. Not come across that before.
Anyway, if I needed to divert, I could just aim for a friendly farmer's field I suppose...
p.s. What IS the correct procedure for diverting? Do you just tell your destination Airfield? What about if you're no where near your destination?