Ambient Lighting?

I've been searching for a good method of adding ambient lighting to a .dif for a while. Most of my larger models look dull like this.

http://forum.returntoblockland.com/uploads/images/2d1719ca327e1a0e4123a26e8a709d48.png

Anyone have good techniques for adding a decent type of ambient lighting through TC to make it less boring?