update Word template Quick Parts with document parser (property promotion/demotion) disabled

We have a custom document management system built on top of SharePoint.  The custom versioning implementation required we disable the document parser to stop property promotion, i.e. uploaded document properties from overwriting the library metadata.  Unfortunately this also disables property demotion so library metadata changes do not write back to document properties.  This is causing various Quick Parts in the document template to not update as library metadata changes.

Is there a way to update custom properties embedded in the document in the itemupdated event triggered by a library metadata change?  Conceptually  - set SPFile.Property["customProperty"] = SPListItem["customProperty"]? The goal is to update the Document Quick Part to reflect the changed value.

Thanks

Fred