The previously mentioned Developer Zone discussion is an excellent source of information for such an application as yours. In addition, I will give you a number of other sources to reference.
First of all, there is a National Instruments Knowledge Base entitled
Using LabVIEW, How Do I Control My Instrument that requires DLL functions that use pointers to compl... This very closely matches your questions. As it discusses, you will want to use LabVIEW clusters as the parameters you pass to the Call Library Function VI.
In addition, there is a Developer Zone discussion entitled
Passing a Variety of Data Types from DLL to LabVIEW This discusses how to read the structures into LabVIEW from a DLL. These resources should help you get started building your application. Accessing DLLs in LabVIEW can be difficult at first, but once you have practiced it, it becomes much clearer and easier to do.
J.R. Allen