Yet another full browser flash question

I am making a full browser flash site. So far so good, everything works, the main movie or content centers on resize, etc.

my main movie or content mc, which contains the main site for other swfs to be loaded in is in a movieclip, registration mark in TL corner.

Here is where stuff starts going downhill. Now I want to make a preloader to preload “the main content”. I cant get my preloader to center in the browser while loading “the main content”. My preloader and maincontent both exist in the root timeline. which is also where the code to center and resize everything is, as well as my preload code.

couple of things ive tried:
A. making the preloader mc the same size as the stage, held open by an invisible square and the loader centered inside this clip, registration TL. Then making a reference to the “loader_mc” in the scale and reposition code.

B. putting the “loader_mc” inside the “maincontent_mc” so that it will inherit the scale and positioning of the “maincontent_mc”, Yet somehow the preloader code doesn’t work from within the “maincontent_mc”

to recap: I need to figure out how to make the preloader in the first frame center with my main content which is on the second frame or another frame,if i chose to “build in” my maincontent, and the script to achieve it.