First: have you checked to see if there's already a LabVIEW library available? This is a very common thing to do, so what I've learned is, there's always a good chance someone else has already done it and made it available.
Second: I prefer whenever possible to write the drivers just using LabVIEW because, if you call the .dll, that's another thing you have to maintain. In my experience, even when it's the right choice for one reason or another, calling a .dll from LabVIEW always causes some hullabaloo down the line compared to communicating with the hardware directly from LabVIEW. What does the camera's manual say about its communication protocols?