How can I get the UR toolbar buttons into the portable version of Firefox?
 

I'm using the PortableApps version of Firefox and the portable version of UR. I'm pretty happy to be able to lug these things around with me on a highspeed USB stick because I work as a contractor on a customer's site who doesn't like me installing my tools on their computers.

I'd like to have those nice little UR toolbar buttons installed in my portable version of Firefox. Is there a manual version of the trick that the UR installation tool performs to get these things to appear?

Dragging and dropping works, I know, but the Firefox toolbar buttons are neat and tidy no matter how all the windows on my desktop are arranged.