WebAdmin is simply the built in ASP.NetWebAdministrationFiles application cleaned up with codebehinds to make customization and refactoring possible.
This is a precursor to a more comprehensive asp.net web administration application that will fold in a lot of the configuration concerns that
have come about in the past 5 years and 3 .net versions.
Point WebAdmin at a site by specifying applicationPhysicalPath and, if relevant, the applicationUrl (virtual path)
It is best if the identity running this application has elevated permissions. Thus it makes sense to launch it with the webdev server or cassini.
If you plan to place it in IIS be aware that impersonation is used and configure the vdir accordingly.
Have yet to track down all the possible cases of the "Invalid postback" exception.
It is caused by a security hole closed sometime after the built in web admin files were written and have not been updated.
When you find one, go to that page and place this in the page directive: EnableEventValidation="false" and post it on the http://spikes.codeplex.com Issues tabe.