I went to
Nokia 6600 Slide iSync Plugin | Paul Bain and downloaded the 6600 Slide Plugin. I followed the installation instructions to copy the file into Home->Library.
After this I renamed every reference in the PLIST files from 6600 to 3600 and also renamed the TIFF file to 3600.
After this, iSync found the Noki 3600 Slide device and it worked!
Thanks to Paul Bain.
Regards
Matt