package MyCode;
use UsefulMod qw(uf_method);

uf_method();

##</code><code>##

package UsefulMod;

sub uf_method {

    # lots of code

    require Backend;       # Also from CPAN
    my $r = Backend->new() # This is where I need a parameter passed
    $r->do_useful_stuff();

    # lots of code

}