package My::Template::Service;
use base qw/Template::Service::Apache/;

sub param {
  my ($self, $request, $params) = @_;

  $params = $self->SUPER::params($request, $params);

  return { $self->custom_params($request, $params), %$params } 
    if $self->can("custom_params");
  return $params;
}

##</code><code>##

package MedBanner::Account::CRUD;
use base qw/My::Template::Service/;

sub custom_params {
  my ($self, $request, $params);

  ## ...
}