I wasn't able to pick the "job" I wanted, as when you are escorted into the waiting area to hear your assignment.
You will be escorted into a room with about 6 or 7 rows of 4. Each spot stand for " Commander, Pilot, Navigator and something else (gosh I can't recall now). Basically all you will have to do is push a button when told.
You will load into the "car" and it will correspond to the spot in which you were standing. There will be a light that will light up and a voice will tell you when to push your button - if you don't push the button, it will go into "auto" and do it alone. You will also need to move your joy stick when told, also, but that is the extent of it.
Just don't move your head - I moved my eyes to see the button I was pushing, and that was it, and never got queasy or light headed - I am so ready to ride it in a few months!