Doc/View and CAchive

OK,

Here's one that seems like it should have a simple answer.

My app is CFormView based. Part of the document are default settings and basic "properties" information for the document. To modify the "properties", I use a CPropertySheet/CPropertyPage. However, it seems to me that when a user presses "Apply" (or "OK" after a change) that this means "Save NOW!". I have a pointer to my CDocument, but need a pointer to the CArchive so I can call CDocument::Serialize(). How can I get the CArchive?
Or is there a different way to call Serialize()? I have tried using CDocTemplate::SaveAllModified() and this works, but prompts me as to whether or not I want to save the changes or not - which I don't want.
Thanks,
KO