The short answer is yes.
The long answer is that it is not for the "faint-of-heart" because of the
First set a reference to the "Microsoft Visual Basic for Applications
Extensibility 5.3" library.
Then look for "Visual Basic Add-In Model" in the VBA help.
There are a few one-line examples scattered around.
If you search the MS KB at
;EN-US;KBHOWTO for "vba
extensibility" without the quotes, you should get back around 32 hits.
Scattered in that list, you'll find a few samples of Excel and Word code
that you can learn from and apply the techniques.
It's just going to take some experimentation.
In this way it will be possible to use patch to modify applications instead
of having to do a new release.