Use coderefs:

my %dispatch = ('a'=>\&first, 'b'=>\&second);
sub dispatch {
 my $self = shift;
 my $command = shift;
 $dispatch{$command}->($self, @_);
}
[download]

Note this removes the OO'ness of it, i.e. no inheritance.
Update:Realized this and was updating just as tilly was replying :)

Possibly another option is to prod Damian into finishing Class::Delegation :-)