Simulating _global variable declaration in AS3

Hi,
I’m working with one old project right now and I have to make some changes in it (AS2).
I want to transform code from AS2 to Flash CS3 (AS3) and now I’m having problems with global variables which are removed from AS3.

Here is a situation:
I have lots of external SWF’s which are referencing to MainTimeline variables. Referencing variables is simple because they are defined as _global in MainTimeline.
How to solve this in AS3?
Can I make global class which variables will be reachable in all external loaded swf’s.
Thanks in advance