Boeing,
This is not directly possible. You best bet is to write a CIN that calls your DLL function. The CIN then returns the function with an extra parameter, the structure. LabVIEW can only return numerics or strings as return values. If it is a pointer to a structure that you need to pass to another function, then you can do that as an I32 return value.
Randy Hoskin
Applications Engineer
National Instruments
http://www.ni.com/ask