You need to accumulate 20,000,000 RSP.
Tips for gaining RSP:
Master events are the quickest (though hardest) way to gain RSP. By doing a four song setlist on master, 1,000,000 is very do-able.
Rehearsing songs before you play them nets you a nice amount of RSP
The more you play songs, the less RSP you get from playing them again. Try to freshen it up a bit with a constant rotation of songs and you shouldn't feel the effects of this.
This will take some time, but it will also help you develop your skill significantly.