Millersoft has created a bespoke Pentaho Excel plugin

This populates a spreadsheet with live operational data directly from defined Cubes or Pentaho Data Integration. This enables the creation of powerful planning applications where users can view actual figures against targets. The spreadsheet gets repopulated each time it is retrieved from the Pentaho repository.

Please note this is old technology. Sheetloom is the most recent Pentaho Excel plugin that delivers free form analytics in any spreadsheet.