Can we run an ad-hoc still?

I'm going to answer my own question, and mainly because it was not as easy to really do.

Create an iteration and call it AdHoc, do not include an environment or a build number. Add your new test case to the 'AdHoc' iteration, then run it and fill in the comments if you want to. It's far too many mouse clicks, but it works as a way to verify that new test steps are in fact sane and populates the time estimate field for the test.