Box for Office is a free add-on and you can open Box files directly from Word, Excel, and PowerPoint, then edit and save to the cloud and share with colleagues using Box shared links without ever leaving the Office programs you use the most.
It is quite simple to use. Download (19MB) and install the add-on, run Microsoft Office application and click on the Box option (Open, Share, Save) to work with your Office files (Word, Excel and PowerPoint). Box for Office Offers the Followings: This add-on is compatible with Microsoft Office 2007 and 2010, and is available to all Box PC users. (via)