Consider using WWW::Mechanize to wrap up the LWP calls for you:

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 fo
+rm elements
$mech->select('widget', \@values); # assumes you get the data from the
+ CSV into @values
                                   # see [fizbin]'s replay above for c
+omments 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',
  }
);
[download]

(Note you might be able to just put widget => \@values in the fields hash, too, but i didn't test it and doesn't explicitly say one way or the other in the docs)