How can the XML (or its ZIP file) for a USPTO number (e.g. `8978162`) be downloaded? Can this be done programmatically (API) and/or manually?

The weekly releases (ca 6,000 entries) contain the type of information I want but not for a specific number. Thus the entry for `8978162` is found in the weekly release as `I20150317/UTIL08978/US08978162-20150317/US08978162-20150317.XML`.