If you want greater control over your query you can use Saiku’s MDX mode. This allows users to edit the query itself rather than use the drag and drop tools available to you. You can either create a blank query or create something close to what you want and then edit the query itself. MDX is a multi dimensional query language and there are plenty of tutorials on the internet that explain how to write and understand MDX queries.

It is also a Microsoft standard so there is plenty of documentation available on the MSDN Network