So I've been trying to get my latency under 100ms for a while now, and this program is getting me close.
http://www.smoothping.com/Check it out, it uses 2 programs called putty and freecap. To route you through one of their servers then to blizz. I use the LA10 server. And my ms has been under 150 for days now. Also its completely free.
BTW korgath server is based in LA if ya didn't know
http://www.wowwiki.com/US_realm_list_by_datacenter