This is the source of a FireFox Search Engine Plugin. It doesn't support sidebar yet, but it does work. Anyone know how to make this sidebar compatible? The favicon for the forum needs to be converted into a PNG too, and hosting needs to be arranged…but it's a start…

<search
 version="7.1"
 name="MIDIBox Search"
 description="MIDIBox Forum Search" 
 action="http://www.midibox.org/forum/index.php"
 searchForm="http://www.midibox.org/forum/index.php?action=search"
 method="GET" >

<input name="action=search2;search" user="">

</search>

<browser
 update="http://www.midibox.org/forum/mbffs.src" 
 updateIcon="http://www.midibox.org/forum/mbffs.PNG" 
 updateCheckDays="7" 
>