Hey, first attempt at contributing, did a search on a few keywords here, so sorry if its a repost
Pretty much, your gonna start here.
jump upto here. (jumping on the lamp thingo, then onto that ledge )
fall down to here. ( your basic way under stormwind )
then run to the big square hole of doom (or is it)
^^ this is where u fall down to, run to the big blueish square over there in the distance.
go to this side of the square hole ( you will be facing SW, or the way you came)
Heres the tricky part, jump the direction i did. ( normal run jump, do not use your mount.)
then TADA!
you land where im standing.
Try it for yourself, its easy
nice place to show off your "how did u get thar!" skills.
Even better, its the same portal you use to leave that room and go out into SW.