Preloading a seperate .swf

I have an intro.swf and main.swf

in the intro.swf i have an intro then an enter button, when the enter button is clicked it goes to a preloader bar and loading text.
is there anyway to preload the main.swf from my intro.swf?

I’m sure i have seen a tut for it on here, but i cant find the right one, thought i would ask for advice befoe i mess somthing up

i understand the code for loading the remainder of a swf to be:

[AS]bytes_loaded = Math.round(this.getBytesLoaded());
bytes_total = Math.round(this.getBytesTotal());
getPercent = bytes_loaded/bytes_total;
this.loadBar._width = getPercent100;
this.loadText = Math.round(getPercent
100)+"%";
if (bytes_loaded == bytes_total) {
this.gotoAndPlay(368);
[/AS]

But that wont preload an external swf obviously.

Any help / advice appreciated