I'm not 100% sure, but it seems that based on the documentation the device conforms to the USB Test and Measurement Class. This means you can use VISA and use it as a message-based instrument. Have you tried to see if MAX recognizes it? If so, you should be able to open a session to it and try a simple command like "*IDN?". The MAX session should also show you the VISA resource name to use in the LabVIEW code. It will be something like "USB0::...".
If the above works, then you would need to write a set of VIs for it. However, based on the command set it seems that it programs very much like a regular power meter, such as an E4419. So, you may be able to pilfer the VIs from the instrument driver from that.
