bbdb-syncml has a number of requirements, and you should pay close attention to all installation steps.
If you don't have a SyncML server, there is no point in installing this package. Without a SyncML server to talk to, bbdb-syncml can do nothing. I use the sync4j server, which is a Java2 Enterprise Edition (J2EE) application.
If you don't use the BBDB, there is of course also no point in installing this pacakge.
Needed to make http calls to the syncml server. Available from here.
Distributed as a part of Gnus and Emacs21. Please see XMLParser section in the emacswiki.
Also available from the XMLParser section in the emacswiki.
Note that xpath-parser.el only works with older CVS versions of the wisent package from the Cedet package. I've checked out a CVS tree from 20020101, and this works for me, although my speedbar and semantic behavoiur in emacs has become a bit strange.
bbdb-syncml uses VCARD as the representation format. You need the files for export and import. See BBDBSyncWithPalm in emacswiki.