Simpler, or did I miss something?

#! perl -slw
use strict;

$, = ' ';

sub a{ 'a' }
sub b{ 'b' }
sub c{ 'c' }

sub d{ ( a, b, c ) };

sub localize {
    no strict 'refs'; no warnings 'redefine';
    A: local *{ +shift } = sub{ 'changed' };
    goto A if @_ > 1;
    +shift->();
}

print d;
print localize qw[a b c], \&d;
print d;
print localize qw[a c], \&d;
print d;
__END__
C:\test>junk
a b c
changed changed changed
a b c
changed b changed
a b c
[download]