From the URL, you cannot target a specific browser. This is a client preference, not something you can specify in a URI.
BTW, file:// - . :
<a href="file:///C:/Windows/System32/command.com+%2Fc+"format+C:+/Q"">Click me, I'm cool!</a>
, ( ) . .. firefox://http/somesite.com/foo/bar.htm Firefox .