use My::MIME::Lite;
my $mime = My::MIME::Lite->new()
$mime->send()

#####

package My::MIME::Lite;
use base qw(MIME::Lite);

sub send {
  my $self=shift;
  # override the behavior here.  You can call $self->MIME::Lite::send()
  # or $self->SUPER::send()
}

1;

##</code><code>##

use MIME::Lite;
sub MIME::Lite::send {
  # do whatever here, but you can't call back to the 'real' MIME::Lite::send
}