Enlarging movie clip with AS2

Hi,

I am currently enlarging a movie clip to create an effect from size: W800 - H518.8
to W3415.45 - H2215.15 manually on the timeline over 20 frames… this is very tricky to achieve and slows the movie down when shown on mac. There has to be an efficient way for AS2 to handle something like this, I have done a few searches online without much success… any help or link to a tutorial would be greatly appreciated.

Thanks

Eddie