[_r.u.s.s.]

you need to put this stuff into header of your website:

<link rel="search" href="link to your xml" type="application/opensearchdescription+xml" title="title" />

then firefox recognizes it

if you want to add an onclick event, you need to add javascript (for firefox that's it)

javascript:window.external.AddSearchProvider('link to your stuff');

specification on the opensearch xml can be found here