MC Width resize noob question

Hey gang, I cant seem to find what Im looking for… although I have a terrible head cold and am probably just thinking poorly today…
I have some buttons on my stage that load a picture when clicked. Everything works fine, but here’s what I want to do…
The images are embedded, made into movie clips. I want them to resize from 1px wide to their actual size while the height stays the same over a few frames. I wanted to try to avoid manually tweening each one, and I figured there might be some (somewhat) easy AS to do this. Any help would be greatly appreciated!
PS im using flash cs3 actionscript 2