My first idea was using lvalue subs, but it didn't work in the debugger REPL so I thought this might not work ... ( bug?¹ )

Trying to find out why revealed that it works pretty well from a source file.

script:

use strict;
use warnings;
use Data::Dump;
$\="\n";

our $x='X';
our $y='Y';
our (@x,@y,@z);

# return lvalue glob
sub lg :lvalue { *x };


print '--- make $x alias of $y' ;

lg=\$y;          
dd \*x;

print '$x= ',"'$x'";


$y='YY';
print '$x= ',"'$x'";


print '--- make *x alias of *z' ;

lg=*z;     
dd \*x;


our $z='Z';
print '$x= ',"'$x'";

@z=qw(Z ZZ ZZZ);
print '@x= ',"qw/@x/";
[download]

output:

--- make $x alias of $y
do {
  my $a = \*main::x;
  *{$a} = \"Y";
  *{$a} = [];
  $a;
}

$x= 'Y'
$x= 'YY'
--- make *x alias of *z
do {
  my $a = \*main::z;
  *{$a} = [];
  $a;
}

$x= 'Z'
@x= qw/Z ZZ ZZZ/
[download]

UPDATE

output from Data::Dump seems correct... globs are just confusing

UPDATE

changed dd *a to dd \*a to make output of Data::Dump less confusing

UPDATE

²) not a bug, just a problem with my debugger settings!