Nice work already with the plug-in, well done.
One installation problem (I think), every time I start Rhino I get a "Preparing plug-in for first use" dialog.
Are others seeing this? Generally this is caused by a crash in Rhino just prior to writing out the registry data when Rhino closes, preventing it from recognizing the plug-in has been identified previously. That's not to say it's your plug-in causing this, but I unloaded all my own and it was still evident (and I want to see if others are already seeing this prior to load protecting the others).
Great work already, looking forward to seeing others reactions and what progresses from this.