Well, sprite and tile editing is already possible. That's how King Z*** and company were added in the Crimson Echoes demo. You have to decompress the graphic you want (there's a topic about how to find the addresses), change it with Photoshop or something then recompress it. It's very easy, but it's just that it's also tedious due to the way stuff are stored.
This being said, I've just remembered a small trick. If you change the palette to Arris Dome (or similar domes) to 22 instead of A, the dome will roughly have the colors of Chronopolis (white, blue, teal, purple). Unfortunately the black tiles will "shine" a bit (from black to dark brown repeatedly and slowly, as if something was breathing).