I should have looked over the documentation more thoroughly, as it's covered by code that's commented "screw you client!" :-)
Basically, in the server.pre() section, add:
req.headers['content-type'] = 'application/json';
This forces the request's Content-Type header to always be 'application/json', so when bodyParser() runs it always assumes it's JSON, and Bob's your uncle. Adding the "screw you client!" comment is optional.
Cheers,
Brad.