its sorta hard to get in but its possible
HMT (Halo Map Tools) or
HHT (Halo Hacker Tools)
A computer(remember my Wraith instructions if u have a mac then it wont work)
Step 1: Halo Map Tools(or Hacker)
Open halo map tools or hacker and open up b40 (Assault on the control room) only b40 not any other map and go down to vehicles and click the + then find the Pelican and click it and go to the Seat tab press the 0 and find P-Driver change it to w-Driver save and go to the Biped tag and click the + and click the Cyborg option and find a check box that says Immune to falling. check that box save and close the map.
Step 2: How to Get In.
this is sorta difficult now to get in start Assault On the control room and go through the level until u see a pelican witch is fire team zulu and then jump off the right edge after u fall off the edge and land try to go under the pelican and when it lands and everyone gets off the pelican hurry and go on the side seat of the pelican and stay on the pelican and for some reason it will crash right by the pelican by the scorpion tank and then u can get off and jump on the right wing and then get to the top of the pelican go on top of the cockpit and it should say Press "E" to enter the driver seat of Pelican too bad it doesnt shoot though