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?
I finally came up with a solution:
A client that wants to build locally (i.e. desktop-builds) needs to install a Build Controller and Build Agent on his desktop machine. Then he needs to pick that controller for the build.
In the build template, the Get activity needs to be deleted, and the Create Workspace activity needs to be replaced with a Get Workspace, to use an existing one.
Finally, remove the command to copy to a drop folder. You're building locally. Not necessary.
Assaf