Hope it helps; it is copied from my walkthrough (page 216)
Enter the southeast chamber
It is a bit difficult to get to the chamber to the southeast of the Knight's Tomb. The reason is that you normally get the message 'Path Blocked!' when you try to throw one of your Teleporter Pyramids up the stairs. Add to that the fact that you cannot throw the Teleporter Pyramid directly from your inventory. You first need to put it on the ground as seen on the picture to the right, and then throw it upstairs. Also notice that you need some Strength to be able to throw the Teleporter Pyramid that far. Once in the chamber there is some loot to find.
