The LazyWeb was not that useful but I was able to find a plugin that does what I need. It is listed in the plugins page on xchat.org but for some reasons I didn’t find it the first time I searched.

The notify channels plugin has every basic feature I need, and it’s also simple enough to be modified adding some other useful features I would like to have.

Thanks Vlad!

Update: the plugin doesn’t work anymore, xchat-gnome doesn’t load it even if it’s listed in the gconf key /apps/xchat/plugins/loaded. The plugin is not even listed in the “Scripts and Plugins” tab in the preferences dialog. Suggestions on how to fix this?