Another option might be to use cURL. I've used this successfully from
Excel to upload files to a password protected site. I used Shell to
run cURL, and waited for it to complete before continuing. The cURL
website (http://curl.haxx.se/) was a pain to navigate at the time, but
it may have become easier. A good starting point is http://curl.haxx.se/libcurl/vb/.

The cURL command line looks something like:

lShell = Shell_And_Wait("C:\Installs\cURL\Binaries
\curl-7.16.0\curl.exe -u userid:password -F action=upload -F
uploaded_file=@""" & _
EXPORT_DIR & "\" & strArchiveDate & "\Your_File.zip""" &
_
" -F submit=Upload http://www.destination_web_site/index.php",
240)

The ShellAndWait function was picked up from
http://www.visualbasic.happycodings....er/code38.html. Nice thing
is, I could use it to launch WinZip prior to launching cURL to cut
down on the file size. There's a perl script runs at the other end to
unzip and relocate received content.