External SWF's, Buttons & Paths?

There is a tutorial I found on kirupa.com on “Transitions Between External SWFs”. http://www.kirupa.com/developer/mx2004/transitions2.htm
I’m new to flash & this really helped me.

My question is about buttons not being on the main timeline with my container & paths.
I’d like to have my buttons slide into the beginning animation so I need to put them in a movie clip & then load the buttons movie clip into my main timeline.
It actually says in the tutorial:

"If your buttons are not located on the main timeline, you will have to change the path to the container movieclip. In this example the buttons are located on the main timeline, therefore ‘container’ targets the container movieclip correctly. Though, if they are not on the main timeline, you must change container to the appropriate path.

Problem is it doesn’t give the details on how to do this & I’m not sure how to change the path & put in the correct path".
Can anybody direct me on this?

Also, does the script need to be on the button itself in this case or does it go on the button movie clip?
Thanks in advance & hope to hear from you.