Perhaps this POST function s is what you searched for:

use LWP::UserAgent;
use HTTP::Request::Common;
my $ua  = LWP::UserAgent->new;
my $res = $ua->request( POST "http://search.cpan.org/search",
                        [ query => 'libwww-perl', mode => 'dist' ] );
print $res->content if $res->is_success;
[download]