I just tried it and it worked for me . I used the "add" function , typed in : C:\Program Files\Mozilla Firefox\Firefox.exe
http://lifehacker.com/ , and the lifehacker web-site opened in Firefox . And IE 7 is my default browser . But the web-page opened in Firefox , which is what I wanted .
Maybe , as you were saying , your specific installation of KeyBreeze is limiting KeyBreeze's functions ?
If no one has ever been to the Lifehacker web-site ,
http://lifehacker.com/ , I would strongly recommend visiting the site . It's where I learned about KeyBreeze !