I just got my shiny new wonderful X800 to play with iSync.
Basically you follow the directions for the Motorola A1000 <a href="http://www.macosxhints.com/article.php?story=20050430050925337&query=a1000">this macosxhints.com</a> article. Instead of using the attached .plist entry, cut and copy the entry for the X700, and replace each instance of X700 with X800.
Good luck!