The only problem I have is that I like to use Yahoo! for search. There are a couple of reasons. One of the biggest is because they support the PHP community so much. Yahoo has Instant Search. They consider it to be an answer for Feeling Lucky, but it does me no good in this case.
I thought I was stuck until I discovered that Yahoo! offers RSS versions of searches. So, I wrote yahoo_luck.php. Its a simple little script that uses SimpleXML to grab a Yahoo! RSS search result and forward you on. I did put some backup in there for times when, for some reason, Yahoo! would not answer. Perhaps some of you Yahoo! guys in the PHP world can poke someone about that.
To use this, just stick it on a server and replace keyword.URL in your Firefox about:config with http://www.example.com/yahoo_luck.php?s=. Enjoy.