Jon,
Your approach to using Google calendar for the scheduling via two code pieces, is a similar way to which I was looking to approaching this. Have you been able to progress it any further?
I am very keen to see how you got to this point – my few attempts to use a private calendar have not been very successful!
I will chip away at this, and hope to get it running, but would be great to see how you achieved the success in the first half of the method.