[Q] POSTing multipart/forms-data

I'm trying to POST multipart/forms-data,
    <http://www.ietf.org/rfc/rfc2388.txt>
where one of the parts is the contents of a file.

The only match I found in the mail archive, is the thread starting at 
    <http://lists.w3.org/Archives/Public/www-lib/1999JanMar/thread.html#361>
and what I'm reading from this, is that I basically have to build up
the body of the POST request in a tmp file or a buffer?

Is this the case?  Or is there a smarter way, using libwww functions
and data structures?

Thanx!


- Steinar