No, there isn't any support to do this directly. The difference between 2D Toolkit and all these other GUI systems is everything is precomputed in 2D Toolkit, and because of that the runtime is very very light. The runtime doesn't know anything about alignments, or texture sizes, or indeed even polygon counts, it simply takes the precomputed data and displays it.
Because of that, it isn't that straightforward to simply display an image like this, as it would mean dragging in a whole load of logic which doesn't exist in the runtime code.
Maybe I could add another sprite collection mode where it takes the texture and uses it and doesn't generate an atlas...