Paras,
I know that this operation you are trying to do, if possible, must be done through MFC, WinAPI. I am not having any luck searching through my MSDN to find what you need to do.
If you have the source for cppsum15.dll, you can derive what to do. But it sounds like you don't, and that the dll is only for viewing. I believe that this information is somehow attached to the file.
I have to believe, given that there is a windows UI for this information, that it can be done programmatically. Search MSs website, or perhaps an MFC system book on the functions that do this. If you find the dll that allows you to make these modifications, you can then simply call this dll in LabVIEW.
Good luck. Please let us know how you make out.