Start at center of movie clip

I have a movie clip container that contains 7 smaller movie clips, images converted to movie clips actually. This is a scrolling banner that can scroll left or right.

How do I start in the middle of this banner instead of the far left? That is, when the script first loads I want to be able to scroll left and right, not just right.

Thoughts?

Thank you in advance,

Cheers, --EA