I would need te same but I'm starting to think that's not possible, it seems Paint.Net doesn't recognize layers of mipmapped images in a user friendly "editable" way, unless you can do it manually maybe, layer by layer keeping in account the right scale maybe, not sure if you can save it correctly and however is quite a bit tricky, if you don't screw up something sending your gpu grinding to death while testing your work, I think it could be a better Idea instead using a separate texture for LoD and, to be more clear, this program works like a charm because maybe it is a charm, to make some quick work it's relly awesome but if someone needs to do something more, well, actually out of the well known commercial ones the only one that can mess with what you mean (.dds) without too much hassle is GIMP, period.
