Hi Eric,
There is no special requirement to use IIS Express other than make sure the client is looking at the right port. (WPF/Winforms)
I suggest taking a look at one of our samples and compare to see if anything is set up differently.
Most of our samples is by default using Cassini, but setting them to use IIS Express will work fine.
Edited by sbelini - 24-Apr-2014 at 12:11pm