As Stich mentioned, RR spikes are the way to go. They are positioned so that when you push the string under one behind a fret the string hooks under it and stays while you are playing, while actually sounding a higher note than the G.
You want them installed by someone who is a proven Banjo luthier and not just any guy in a music store who says he can install them.
It is not necesary to capo up to the suggested key to learn the song. The just follow the tabulature and it will work: the only difference is that you will be playing it in G instead of the higher key. I tend to learn most things without a capo first and then add the capo later