Good news - you can. Just open the config, goto the plugins section, and you can drag and drop the listed plugins to change their order, and create subfolders into which you can drop plugins into if you want multi-level menus (mine are currently set up as Television, Music, Video, and Extras).
If you use task images for the plugins, you can use task images for the submenus as well, if you give the image the same name as the menu (eg Extras.png) and put it in the Custom skin subdirectory.