I've textured the slug in modo, it's becoming really nice, I think at least! I removed the "horror creature like" teeth for a much more funny tongue. Next time I'll try a full free software pipeline with MeshMixer, Gimp, Blender and LuxRender, which seems to be an incredible render engine (maybe a little slow with 4 cores...) .
Now it's time for the body, the hardest part!
Hope you like it.