How do I import an .swf so it is centered on the stage?

How do I import a .swf so that the entire thing–all 50 frames of it in the case of the animation I’m importing–is centered on the Flash Stage? (I am using CS5).

When I import it now it’s automatically positioned in the upper left corner of the stage. And when I try to select all frames and align it to the center in the properties manager it will only center one frame of the 50-frame .swf at a time.

This is my first post and I thank anyone who can help in advance!

Jim