use WWW::Mechanize;
my $mech = WWW::Mechanize->new;
$mech->get($url_of_form);          # NOT necessarily the target of the post
                                   #   -- this is page w/the actual form elements
$mech->select('widget', \@values); # assumes you get the data from the CSV into @values
                                   # see [fizbin]'s replay above for comments on %widget
$mech->submit_form(
  form_name => 'name_of_form',     # or use the form_number param
  # form_number => 3,
  fields    => {                   # simply set the other form values here:
    username => $username,
    created => '1126175051',
  }
);