StepR
,
According to the information on the IRM webpage, tickets won't go on sale until early next week (they say the 27th). At that time, they will announce what the prices are, and probably have an online order form as well.
From what I have read, seating is very limited, so once they do go on sale, you should probably try to order them as soon as you can if you are interested in riding.
--Brian