Were you not able to get the modal dialog working using the method that we spoke of on this thread: http://forums.ni.com/ni/board/message?board.id=330&message.id=14315&view=by_date_ascending&page=3
If not, did you try the example that ships with TestStand for using modal dialogs? As I said on the post, I was able to successfully call your VI as a modal VI from TestStand. Please follow those suggestions and let us know if you are not able to get that working.
Thanks,
Andy McRorie
NI R&D