Okay I learned this when I was looking for new exploits. P.S have to have aspect of the cheeta
1.when you enter stormwind you should go in a little tunnel
2. in the tunnel if your standing looking in the way to get in stormwind take a right there should be a little bump that ledge to the right run and jump right when you are on the lump jump it should get you on the ledge
3. when you get there go to the right until you get to the spot halfway up to get under stormwind faster