To add files or images to the 12 hive simply add a SharePoint/ Module by the nameTemplates, to the root of the SharePoint Project created with VSeWSS 1.3 and below that att the folder Images and latter eg: MyWebPartImages. then simply drop the files to this folder in Visual Studio and deploy your project and the files should now be visible in you 12\Template\Images\MyWebPartImages folder.

note you can delete the files created below the Module folder before adding the Images and latter the MyWebPartImages folder with you files in.