This video shows how to use InfoPath to create a custom Document Information Panel to be used with Microsoft Office Word This demo shows how to: create a SharePoint content type, reference SharePoint list data in the content type, assign the content type to a document library, design an InfoPath form that uses the content type, publish the InfoPath form to a SharePoint Document library and use the newly create Document Information Panel.

The rest is here: 
How Do I: Create a Custom Document Inspection Form?