getURL pop window activated without a button? impossible?

Is it possible to have a javascript pop up window function in flash without having it assigned and activated by a Button?
For example when the animation enters a certain frame it pops a new window. I would like to have a email invitation form pop up in a seperate window once the main movie loads. To give a little more background. I have an index page that opens a main movie in new 600x400 resize=“no” window and I would like the javascript in flash open the 3rd email invitation! The invitation is only temporary and I dont really want to add a button to the main movie. Is this impossible?
The actionscript I’m using causes the new email invitation to replace the main movie in it’s 600x400 window.