Thanks to everyone who replied.
I modified the code to pan~ from the motex externals to implement the algorithm by Michael Gogins found here: http://www.csounds.com/ezine/autumn1999/beginners/ (thanks steven)
It makes a powerful wrap around your head kind of pan which is just what I was looking for :)
I only changed two lines in the source code but if you want to play around with it I put the code up here: http://metm.org/pd/pan_gogins~.tgz
Thanks again,
--Marco