Hi Bryan,
We are still working on the full documentation for this feature.
The first piece of important advice I would give is to make sure when you create a new CustomPanel in DashBoard that you use the 'Blank XPression CustomPanel' template. This is part of the creation of a new custom panel so the steps would be:
1: File->New->New CustomPanel File
2: A window opens asking you for the file location and file name, it also has the template to use, make sure that you pick the 'Blank XPression Custom Panel' option.
There is preliminary documentation that you can download at:
http://www.rossvideo.com/software/dashboard/Beta/DashBoard_Release_Notes%206%202013_02_13%20T17_40_XPression.pdf. It is a little out of date now but it has the basics in it for you.
Troy.
#DashBoard