Per http://support.microsoft.com/kb/305144, the UAC code for a Normal_Account is 512. Make it 514 to disable the account.

my $ldap = Net::LDAP->new($host) or die "$@";
my $bind = $ldap->bind($bind_dn, password => $bind_pw);
my $result = $ldap->modify($user_dn, replace => { userAccountControl =
+> '512' });
$ldap->unbind();
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