Here's my quick fix:

sub _make_request {
    my ($self,$request,@rest) = @_;

    # fake a proxy
    $self->proxy( [ undef ] );


    my $uri = $request->uri->as_string;
    my $response_content = "foobar\n";

    # we'll probably have to build in support for redirects at some po
+int
    my $response = HTTP::Response->new(
        defined $response_content ? RC_OK : RC_NOT_FOUND,
    );
    $response->request($request);
    $response->push_header('Content-Type', 'text/html');
    $response->content($response_content);
    return $response;

}
[download]

It's a hack i know, but it gives me this output (with some added debug code (LWP::Debug))

LWP::UserAgent::new: ()
LWP::UserAgent::proxy: ARRAY(0x1ccb53c)
LWP::UserAgent::proxy: undef
LWP::UserAgent::proxy:
foobar
LWP::UserAgent::proxy: ARRAY(0x1da22b4)
LWP::UserAgent::proxy: undef
LWP::UserAgent::proxy:
foobar
[download]