Tween the colour of a MC

Hey I wondered if anyone knows a way to script a tween on a MC so it’s default is greyscale, when I roll over it becomes full colour and when I roll out it returns to greyscale.

I know I could do it by having 2 images and fading the _alpha on the top image, but I’d wanted to load just one and us AS to control it’s colour values.

I’ve been playing with MC_tween as well but so far haven’t managed it? Flash 8 has an adjust Colour filter in it but I can’t seem to find anyway of adjusting this using AS?

Any thoughts???