package MyModule;

use vars qw(@ISA);
BEGIN {
   @ISA = ...;
   *MyModule::Super::ISA = \@ISA;
}

sub dostuff {
   if (...condition...) {
      if (my $method = MyModule::Super->can('dostuff')) {
         goto $method;
      }
      ...die?...
   }

   ...
}

##</code><code>##

package MyModule;

use vars qw(@ISA);
BEGIN {
   @ISA = ...;
   *MyModule::Super::ISA = \@ISA;
}

sub dostuff {
   goto(MyModule::Super->can('dostuff')) if (...condition...);

   ...
}