As the Active Directory UDF - Help & Support thread has grown too big, I start a new one.
The original thread can be found here.
I modified some of your functions to add a user from another trusted domain:
Func _AD_ExObjectExists($sObject = @UserName, $sProperty = "", $sHostServer = $sAD_HostServer, $sDNS = $sAD_DNSDomain)
If $sProperty = "" Then
$sProperty = "samAccountName"
If StringMid($sObject, 3, 1) = "=" Then $sProperty = "distinguishedName"
EndIf
$__oAD_Command.CommandText = "<LDAP://" & $sHostServer & "/" & $sDNS & ">;(" & $sProperty & "=