I got this to work — all of the changes that you describe above were already added.
I had to add a line to both the modules and handlers sections under <configuration><system.webServer>. This is described in this post – http://documentation.devexpress.com/#AspNet/CustomDocument7540. (Be sure and change the version number to 9.3.3.0.)
I assume that this is required for IIS v.7.5.