So go to the area where there's a giant well/hole. (it's big blue and round. Can't miss it.)
By the time you get to the part where you're stuck, there should only be one door locked and the other 2 are unlocked. The one door that is locked requires a lantern to shine into it and the door is somewhat down a corridor and down a set of mini-stairs (same area).
Go to the area where there's a rotating crank on a second level that rotates the linear bridge.
Go to the left of that, there should be a staircase blocked off by the spike looking wall that comes out of the ground.
Use the trainer to hover over it. Open the lever and jump down to the bridge and go into the recently openned door.
Hopefully that makes sense.. If there's problems I'll post screenshots.
Sorry for the late reply Ive been away Im stuck at the 2cd platform thingy place lol where you have to throw a stickybom thingymajig so that the lever can come out and then you can jump onto it and push it and fight the boss.
Here's the pic, when I throw the sticky it explodes but does nothing...
Im going to message THQ support hopefully they can help