It turns out that if I delete the DACL before populating it with the Add method, it works.

So the code now looks like this:

use Win32::Perms;
use diagnostics;
use strict;

Win32::Perms::LookupDC( 0 );

my $path = 'c:\temp';
my $login = '\\hostname\testuser';
my $Dir  = new Win32::Perms($path) or die "new: $^E";
$Dir->Remove( -1 ); # added this line
$Dir->Add($login, CHANGE, ACCESS_ALLOWED_ACE_TYPE, OBJECT_INHERIT_ACE 
+| CONTAINER_INHERIT_ACE ) or die "allow: $^E";
$Dir->Set() or die "set: $^E";
$Dir->Close();
[download]

Now I need to find out a way to extract the existing ACL, add the entry I want, and re-apply the whole thing...

Schlika.