Hi Zaheer,
Yes, it's a little unfortunate. I'm not sure why the COM add-in was not developed in a way that will expose its functionality to VBA, but I can tell you there isn't much 'demand' for it , in other words: not so many customers/users ask about it or seem to need it.
Normally I'll suggest you post this request for a future feature enhancement to our ideas site (https://ideas.rallydev.com) but currently CA is already working on a new version of this add-in to replace the current version. My understanding is that it may become available for beta soon. Posting ideas for features for this current technology of the add in will almost certainly not be addressed.
You may want to spend some time and see if you can find a way to invoke the Ribbon's object function. As said, I couldn't find such a way, but it may still be possible.
My apologies I can't help more.
Sagi