Bobbin work is done with threads that are too thick or uneven to go through the needle, or to stretchy or delicate to go through the upper tension. I wouldn't try it on a longarm - depending on the thread, I would worry that it couldn't handle the higher stitch speeds of the longarm. You would also have to significantly adjust the tension of the bobbin case.
What thread and what project are you considering? With bobbin work, your fancy thread ends up on the back, which is the opposite of how I think of longarming. If you could give more details of what you are considering, people might be able to give better advice.
Edit: felinefanatic posted while I was typing my reply. I believe her that it can be done, but I would be cautious... I really think of it as a domestic machine technique.
Last edited by Jennifer23; 08-24-2016 at 09:15 AM.