Reusable preloader for loadMovieNum via buttons

Hello there, I am using loadMovieNum via buttons (on level 0) to load external swfs into my main movie (into level 1).

What is the proper AS2 to preload each swf after the button calls it to loadMovieNum? I would really prefer the most simple solution possible since too much code is confusing to me. I will not be using a container clip, just simple levels and loadMovieNum so please do not reply if your solution is to use an empty MC.

Thank you so much!