Hi Joe,
RE: parsing:
This is still a ways out. (as you can see from my previous comment, I am quite a bit past August as well...)
I was hoping to secure a grant so that I could take a leave of absence from work and complete this, however it did not work out. Would you be interested in helping to develop parsing?
RE: VBA code is something that is not covered in the specification. However it is possible. This article has an easy to follow C# example that shows which content types and relationships are needed, and packaging conventions do allow for arbitrary (e.g. non-spec) parts to be added to your zipped xlsx package.
However - considering restrictions in Office regarding unsigned macros, getting XmlDigitalSignatures up and working is probably a requirement.
Best regards,
randym