The downgrader you're likely referring to is not intended for modern devices (and will effectively not work there anyway). IIRC, there's a specific thread detailing downgrades on modern devices, but it isn't for the faint of heart.
EDIT: Okay, I was remembering older stuff.
This should be fairly streamlined. Caveat emptor, YMMV, etc.
(Do read through the original, manual thread, though).