I know that the short answer is "you can't". Desktop builds are no longer a part of TFS 2010.
However, I figure that I can somehow, if I install a build agent on my machine, and direct the WF to not get the latest version or a shelveset, and use the existing workspace, I should be able to fake it.
The problem is that between the theory and practice is a large gap in my knowledge. Can anyone think of a way this could work?