Here are some resources that can get you started:
Using the ActiveX Controller Wizard in CVI:
http://digital.ni.com/public.nsf/websearch/4B597F188B89B6DD862568970071F2FC?OpenDocument
KB on Matlab and CVI:
http://digital.ni.com/public.nsf/websearch/C0E3AC06575AB56C86256842005FEFFF?OpenDocument
ActiveX features supported by CVI:
http://digital.ni.com/public.nsf/websearch/610540BB3EA4EBDD862568960055E498?OpenDocument
For starters, I'd also suggest to take a look at the matlabdemo example that comes with CVI. You can find it under samples\activex\matlab.
Regards,
Azucena