First of all, you have to start jumping the blocks to the right (in order to go in the small room and get the key).
After that you have to go all the way back to the doorway that you entered from. Grab the ledge and shimmy across to the left - drop down on the block below you.
Then you have to work your way across from this side. At one point you have to look down and drop to a lower block instead of trying to make the long jump. Once you get all the way to the end, it will appear you can't jump high enough to get up to the gate. However, there is a block in the wall that you can pull out.
If you are still stuck - e-mail me.
[This message has been edited by Jamison (edited November 20, 1999).]