....
    my ($class,$alias_for) = @_;
    install_sub(
        $class,
        'find_ids', 
        sub {
            my ($class,$params) = @_;
            do_something_with($alias_for);
            # $alias_for is a lexical which defined outside this sub
            # which uses deep binding so that it is available
            # when this sub is called

            return $class->SUPER::find_ids($params);
        });
     ....

##</code><code>##

  eval "package $class; sub find_ids { ..... }";

##</code><code>##

    ....
    my ($class,$alias_for) = @_;
 
    # Store the original find_ids here
    my $original_find_ids = $class->can('find_ids')
      or die "Super-classes of $class don't define sub find_ids";

    install_sub(
        $class,
        'find_ids', 
        sub {
            my ($class,$params) = @_;
            # Do something with $alias_for;

            # Use the original find_ids as a function
            # $class as its first argument, so it thinks 
            # that it has been called as a method
            return $original_find_ids->($class,$params);
        });
     ....