Chances are someone already has taken the time to tell you how, you just need to find out where - trying searching Google using search terms like "AS2 XML tutorial". Post again if you have a specific problem you need help resolving and include the code that is giving you a problem.
attachMovie is a library-related loading function, not an external file, so you might need to explain more about your intentions of loading an external swf and how it relates to loading a library object.
So what I'm thinking of doing is through the main draw for swf another swf xml attribute.
This loaded swf will be introduced within an attachMovie.
Every time I load a new swf external, will within that attachMovie