it's handy, but you don't actually need a special tool to finish your binding.
search You Tube.
there are a lot of good tutorial videos there that will show you how to do it without a special tool.
this is the video i found last year that helped me figure it out:
http://www.youtube.com/watch?v=HQcmbv43nH4
one note: if you are working with straight cut binding (not bias), make sure to leave
no more than the 1/8" gap she recommends.