Logic Pro 8 can I assign a fader from my control surface to tempo


Hi gang,
I was wondering if one could assign a fader to write tempo changes,
I'm working on a classical piece and I'd like to ebb and flow the tempo a bit, but instead of just writing dots on the tempo track, I'd like to 'conduct' the tempo.
I figured a fader on my control surface (a DM2000 or a Euphonix MC Control), but in reality can I assign anything to control the tempo and record those changes realtime?
As always Thank You
Rock on Y'all