Questions and discussion for this lecture live here. Fire away by hitting Reply below 
We found in this lecture it is very simple to add spring DoF to the structure. What is the procedure to add a prescribed displacement?
Yes - prescribed displacement can also be implemented relatively easily - although a little heavy to get into here. Perhaps I can cover it in a tutorial article. In the meantime, take a look at this reference which another ES member forwarded me recently.
I hope that helps, until I can get around to covering this myself.
Seán
Perfect! Thanks for your reply