Is it possible to add a LWP handler to a Mechanize agent?

I tried:

  $mech->add_handler(response_header => \&response);

and got:

  Can't locate object method "add_handler"
  via package "WWW::Mechanize" at test.pl line 134.
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Is there a hidden way to access the LWP user agent object through the mech object?

UPDATE: I've just updated Mechanize from version 1.54 to 1.58 (and some dependences), and my test run as expected. Thanks anyway!!! ;-)