Please, Help Me

If I have an uneditable swf file ( one.swf )
and I like to load it from another file ( base.fla)

my question is, I want to put a preloader in "base.fla" to load "one.swf"
the problem is that the preolader can know the size of data in the frame but not the size of the loaded file. so, Please HELP me.....

I think it's the same if I want to load an image. How can the preloader know the size of the loaded image??