They probably block the port used for XMPP communication with QL's XMPP server.
We had a good vpn here in Orlando that would allow me and a few others ping 15 to alt (when atl worked), then routing on the vpn went meh
Try these services out, in this order:
www.wtfast.com (Proxy gaming service, first 30 minutes connected for free so you can test).
As far as VPN's go, I've tried www.hidemyass.com (massive ping spikes and PL), www.purevpn.com (Irritating to setup because they have to allow ports on their side for QLive to function on their network), and my favorite, www.fixmylag.com
www.fixmylag.com offers two methods to alter your routing to gaming servers, through proxies and vpn. Their VPN service is very solid and ping jitter is acceptable, I'd definitely give them a try, worked well for me. When I had cable, I pinged 60 to los angeles servers, using fixmylag.com proxy or vpn, my ping dropped to 15-22ms.