Nono, pyramids work: If you stand at the east wall and throw it south over the gate => you can enter.
Kiya
http://www.kiya1.de/images/Divdt_Verdpoly1.jpg.htmlhttp://www.kiya1.de/images/Div_Polymorph2.jpg.htmlsee? otherwise I wouldn't have found out where the 2nd polymorph chest is. Look at the 1st pic => you see 2 gates, one showing north and the other south. Just toss your pyramid over the south gate. Not far away, there is a small place, not restricted by the cross. But you need the 2nd one in your inventory for this. Teleport over then and after you're done => toss back. INTO the east area again.