On my N5.8 I have a similar setup to what Andrew described. It work good. If I recall, the Murray's catalog has a picture of the setup.
I have seen some who have a bull's eye instead of the cam cleat 15" on the crossbar, and the rotator line was led a little farther out on the crossbar, such that it could be adjusted while out on the wire. I have never sailed with that setup, so I cannot say how well it works.
David Rogers
Nacra 5.8 w/spin