How can I do the below?

use a custom GINA.DLL file to mask the real domain name on the Windows XP login dialog.

I would like to do this as opposed to re-naming my domain which is now not possible as exchange 2007 has been implemented.

But I do not know how to modify or which part to modify on the gina.dll or msgina.dll.

Any help would be greatly appreciated.

Thank you.