ok first off i don't know if this has been posted before and i don't feel like searching to see if it has, i just want to help some people out if it has been posted though i will delete my topic or whatever.
Ok to do this you need to know how to wall jump.
you just go to the gate that is on the side of the room where the tunnel is then you just use wall jumping to climb up and after a couple of jumps you will be able to jump over the gate