Isn't there a release candidate out for FF 3.7? If so can you confirm that WebSockets support is in there?

No, you don't need to. Try putting this in a hex editor. You'll see a http handshake. The first part you need to send is "GET " which is the same as sending the following bytes: "47 45 54 20". It's just made a bit "simpler" so people don't get the encoding wrong (non-ascii characters, etc...).