The back door links only allow ranked rounds to my knowledge (I have only played the course twice -1 x F9 and 1x B9.
It appears you can play in practice mode in a multiplayer game though......
On the main game client under explore courses (left bottom) click on see all courses.
This brings up EH......click create group and then choose your options. This is also how you set up A/S obviously.
I presume if a mate joins, he could bail on the first leaving you to play the round out.
Not sure if it is possible in single player mode though....someone might have worked out a way in....but why bother, just play it as ranked via the back door links.