$agent->click($method_field, synchronize => 0 );

##</code><code>##

    $agent->click({ dom => $method_field, synchronize => 0 });

##</code><code>##

use strict;
use WWW::Mechanize::Firefox;

my $url   = "http://tools.immuneepitope.org/tools/bcell/iedb_input";
my $agent = WWW::Mechanize::Firefox->new(
    activate  => 1,
    autoclose => 0,
);

my $method = 49;
my $seq = "ARRRSFASDATRASDFSDARASDAGADFGASDRFREWFASCDSAGAREW";

$agent->get($url);
if ( $agent->success() ) {
    #sleep(5);
    print "Retrieved $url\n";
    $agent->form_name('form1');
    #$agent->set_fields( 'sequence' => $seq,'method' => $method);
    $agent->field( 'sequence' => $seq );
    my $q = sprintf '//input[@name="method" and @value="%s"]', $method;
    my $method_field = $agent->xpath( $q, single => 1 );

    warn "Method";
    $agent->click({ dom => $method_field, synchronize => 0 });
    #sleep(5); 
    warn "Submitting";
    $agent->submit();
}