First, you can look at this
ActiveX and LabVIEW
http://zone.ni.com/devzone/cda/tut/p/id/2983
Use of ActiveX with Microsoft Office can be an extremely powerful tool in LabVIEW. The developer of any ActiveX server or container is responsible for providing the documentation for what is supported. In the case of Microsoft Office, you can find the necessary documentation in several places. The best place to get started is by visiting this Microsoft document: How to find and use Office object model documentation.
http://support.microsoft.com/default.aspx?scid=KB;EN-US;Q222101&
Where Can I Find More Documentation on Microsoft ActiveX Methods and Properties?
http://digital.ni.com/public.nsf/allkb/C4ABFFC75C5E6A7186256C4B0083BF3C?OpenDocument
How do I determine the class hierarchy of a MS Offic application's ActiveX implementation easily?
An application's documentation should be responsible for outlining the details of its ActiveX implementation, how objects are organized relative to one-another, what the methods and properties of those objects are, etc. An easy way to get a handle on some of these things with Microsoft Office products such as Word and Excel is by recording macros. All you need to do is start macro recording, carry out the set of tasks manually that you eventually want your application to remotely perform, and then look at the recorded macro. You will see that the macro editor often only shows you the most "recent" objects, those that own the actual method(s) you called or properties you used, but you can typically get a handle on the overall structure by trying some different things. Once you know the general structure and are aware of the organization of the application's objects, it is quite a bit easier to invoke those methods and actually control the application as a server with minimal time wasted.
Finally, as a good starting point, you can search labview example finder with the keyword "ActiveX". There are some examples for your reference.
