Well, I personally wouldn't recommend modding LoS at this point if you're not intending to improve the game itself somehow. Not because it wouldn't be possible to do a lot of things, but because doing a lot of things that LoS itself doesn't need can be hard and frustrating. For example, disabling cel-shading requires you to write some GLSL shader code, and placing 3D models on a uniform grid requires some Lua coding. You'll likely also need a lot of patience since many things, such as the editor, are broken at the moment, and I can only fix things so fast.
That said, if you work on stuff that is plausibly useful to LoS itself, you won't have to write any code if you don't want to. If you contribute your creations to LoS, you don't actually even need to integrate it at all yourself. In that case, it'll just magically appear in-game in a few days after you have submitted it for inclusion.
Anyway, in this specific case, I'd say that something like Blender Game Engine would probably be a less painful approach. If he can live with cel-shading and wait for the editing features to get fixed, LoS might be an option too.