Basic Ocamlnet Question

[Peter.Gregory@cis.strath.ac.uk]

Hi,

I've just started messing about with ocamlnet, and have instantly run 
into a problem.  I was trying to write some code that interfaced with  the
backpack API (http://developer.37signals.com/backpack/).  I tried 
tweaking one of the examples just to get a page listing, and wrote the 
following:


open Http_client.Convenience;;

let get_and_print url  =
   let s = http_post url [("","<request> <token>mytoken</token>
</request>")] in
   print_string s;
   flush stdout
;;

let () = get_and_print "http://pg.backpackit.com/ws/pages/all";;


However, this doesn't work, as the header for the request should be 
"Content-Type: application/xml".  How do I set the header for my request 
in ocamlnet?

Thanks,
Peter.