A GRT on packed negativity indicator and value seems to work.

use 5.026;
use warnings;

say for
   map { 
      unpack q{xl>}, $_;
      }
   sort
   map {
      my $neg = $_ < 0 ? 1 : 0;
      pack q{Cl>}, $neg, $_;
      }
   -4 .. 4;
[download]

The output.

0
1
2
3
4
-4
-3
-2
-1
[download]

I hope this is useful.

Update: I just noticed that Tux posted exactly the same method while I was posting this.

Update 2: Ah! Not quite the same, negativity indicator not required apparently.