Hagatha, to get to the island:
Hop on teleporter, you're on the east island. Then drop your pyramid. Use the teleporter pad to return to main island. Now Click on your pyramid in your inventory to get to eastern island again. Now step on teleporter pad there => you're on the north island.
Kiya
If you look at the pads closely => they have small triangles indicating where your journey will go. So you have to "turn" the east pad by using it once. Then hopping on it in the way I described will get you to the other one.
http://www.kiya1.de/beyond/act2maps/Act2telephop10.jpgPlease, tell me, if this diagram link helps you.