I just submitted the proxy patch to LimeWire. I'm almost sure you will get past this Sandvine thing by using your ISPs http (or socks) proxy. (Almost all ISPs offer http proxies, maybe you'll have to dig a little to find the address).

If you can't accept incoming connections or force your IP address, this patch will also proxy your uploads (unlike morpheus ;-) ) and it will also proxy all outgoing gnutella connections (also unlike morpheus )

I'm not sure if LimeWire will implement this, though.