Import Modified Source Files

I have CS4 software, the web designer suite and css sculptor with all of the latest versions. I have downloaded and modified the source files (Texture layout) using fireworks (png files). These are saved locally but I have no idea how to import them into css sculptor for use with Site Assist professional. Because the original zip file contains two other zip files (home and sub pages) as well as xml, photoshop and fireworks files, I don't know what to zip up for importing (or do I even zip my modified files up?). The readme directions aren't extremely clear as to how to go about this. What I want to do is to have my modified files be available from the Site Assist pro wizard, throughout the construction of the site. I can then revert back to the default Texture layout. Do I rename the included xml file? Do I zip my modified files up with the xml file, then point to that zip file from the css sculptor import? Or is there a way to export/copy the files directly to the Site Assist Pro wizard, in effect bypassing CSS sculptor?

Or am I going about it all wrong? Should the modifications to the Texture layout template be made from withing Css Sculptor? I certainly appreciate any help as I have no earthly idea what I'm doing.
Matt