<search
name="Digital Inspiration"
method="GET"
action="http://www.google.com/search"
queryCharset="utf-8"
>

<input name="q" user>
<input name="sitesearch" value="labnol.blogspot.com">
</search>

http://labnol.blogspot.com/2006/09/learn-to-create-firefox-search-plugin.html

example code only... save to [path.to.profile]/searchplugins/

Create a Firefox Search Plugin

plugin, search, xml

XML