When I developed this app (in C# Visual Studio 2008) I asked the same question (actually managed to find an answer on the MS forum, for which I deserve a prize of some sort). The answer from MS was that the only way to set keyboard shortcuts to your own methods is to write a macro which invokes the method (via COM. obviously) and set the shortcut to invoke that macro.
This is really not the answer I want to hear. VSTO makes it possible to build a really nice application with very good use of the ribbon, etc., but then you have to go to the trouble of exposing the entire thing through COM and build another interface into it via the macros. Which, in addition to being a waste of time, totally circumvents all the security that MS have built into support of VSTO Add-ins.
My question is: Is this really necessary (the whole COM/macro thing), or is there a way that I can assign a keyboard shortcut to my own ribbon items? Word 2007? Word 2010?
Thanks