I am new to WAIK, and am trying to figure out how to build a WIM image from the Windows 2008 R2 ISO media.
So far I have been unsuccessful in finding this information.
Is this possible, and if so, what am I missing from the TechNet documentation?
You don't need to build a WIM image, it's included in the install media. It's located at \sources\install.wim. That's what you manipulate with DISM/MDT.
The WAIK documentation has a step by step document of how to image a system. By default this is at C:\Program Files\Windows AIK\Docs\Whitepapers\stepbystep_itpro.htm
depending on what you are trying to deploy i would encourage you to also look at the microsoft deployment toolkit, which automates much of the WAIK.
the command to capture an image from the reference install is imagex.exe /capture d: d:\myimage.wim "my server install" /compress fast /verify