Ok for anyone who's interested this is how I've done it.
Every plugins has 3 files,
- Plugin_TopArtistsInfo.xml, with some information about the plugin: name, descriptiong and id.
- Plugin_TopArtistsWnd.xml with the window(s) for the plugin.
- Plugin_TopArtistsJs.js with the Jscript functions for the plugin.
And last but not least the manager itself (currently only listing of plugins)