There is an undocumented feature allowing you to specify a custom data directory. It was originally added in version 220.127.116.11. Here's the information:
Added the ability to change the location that Scrapbook MAX! uses to load and save projects. By default, the "Scrapbook MAX!" directory inside of your My Documents folder is used. If you want to change this location, first create a text file called "user.ini" and place it in ...Program Files\Scrapbook MAX!\Data. Inside of this ini file, add the following 2 lines of text:
where "MyNewFolderPath" is the new folder path you would like to use to save your files (eg. BaseFolder=D:\Scrapbook MAX!) If you still want to access all of your current files, go into your current documents folder and copy the 3 folders "Projects," "Published Files," and "Templates" into your newly created folder.
Please note that though this is a feature of Scrapbook MAX! 2.0, it is an advanced configuration and is not officially supported by us.