Not that you should not take a look at the ATP course material, but you will not find a specific example of what you want there. If I recall correctly, the thread to which Steve linked was part of a conversation that also took place, in part, in the Autodesk Discussion Groups, where the conclusion reached was that while you can retrieve defining points stored in the object model in a Formula property, extracting the coordinates does not appear to work. I never received a response to
this post in the Autodesk Architectural Desktop Customization Discussion Group, which uses a Wall object and tries to determine the Z-value of the Location property. That post shows the code used to get the object and the Location property. You might have a different experience using 2007 [rather than 2006] and/or with a mass element [rather than a wall].