Client code:
my $url = "https:\/\/acct:pass\@ftp.mydomain.com/cgi-bin/upload.pl";
my $ua = LWP::UserAgent->new;
$ua->agent("MyApp/0.1 ");
my $file="c:\\filetoupload.txt"; 
$res = $ua->post($url,
[ "ac" => 'upload',
"file" => "$file"
]
); 
print $res->content, "\n";