LWP::UserAgent - 03 - custom referers

Nothing easier:

# create request object, passing method
my $req = HTTP::Request->new(POST => "$POST_URL");
    # this is used for post
    $req->content_type('application/x-www-form-urlencoded');
    # line to post
    $req->content("lang=it&descrizione=$letters&numero=&CheckExt=N");
    # referer URL
    $req->referer("$REFERER_URL");

    my $res01 = $ua->request($req);