You can make a gravity lift, look at the picture, and take away the glass as it isnt neccessary, you have lots of circular planes going up together, and then the top one gets moved back to the bottom and it carries on, and each gap between the planes would be the height of a master chief.
Do you understand? and
http://www.halomc.com/files/AnimScen.zip is a great video tutorial on how to do a single lift, but for what you want you will use alot of these in a rotary sequence, go up, then when it reaches top, quicly moves under the one at the bottom, then they all go up, and the top one goes under the one at the bottom, and so on. You understand?
Then for it to go back down, you could use a teleporter... Have another gravity lift. I would use a teleporter to get down, because most people wont go down with the lift, they will fly their shee down.