Possible to set up a dev environment for a custom story instead of map?

[GraphicsKid]

Run it in windowed mode (change this in the options menu). Then to use the mouse outside the game, just pause it or bring up the (f1) debug menu.

EDIT: And yes, I too was actually about to ask the EXACT same question here: can we setup a dev environment for a custom story?

EDIT2: Well okay not the EXACT same thing, but how do you get it to run a map from within a custom story's directory?