If it asks for those on its standard input, then use:

open CMD, "|foo -args file" or die;
print CMD "$username\n$password\n";
close CMD; die "bad exit $?" if $?;
[download]

If it instead needs to use /dev/tty, you'll need to get into the Expect module, or something else that handles pseudo-tty's.

-- Randal L. Schwartz, Perl hacker

P.S. I didn't expect those three lines to line up perfectly like that. I was using a proportional font to enter it. Really, I was! Honest! {grin}