Well, I haven't seen any tutorials on it actually, its just one of the tools I played with till it worked!
In a nutshell, this is how you get it working.
1.)Split your blender window into two, and open the UVMAP window. On the UVmap window's toolbar, select "image" and then "new". This opens a dialog that you can specify your image size in. Size it how you want (512x512 is good). Save it.
2.) UV Map your model. Go to front view, select the model and press "F" to go to UVMap mode. Press "U", and select "Sphere from View" or the type of unwrapping you want. This doesn't really matter, because any of them, except cube, will do fine. Your unwrapped model should appear in the UVmap window.
3.) Go to "Texture Paint" in the mode option box. The same select box that has object mode, edit mode, weight paint, vertex paint, sculpt, etc.
In the edit tab you will have all the relevant options like brush size and all that.
Paint away!!
basically all you are doing is unwrapping the model, making an empty image for you to paint on, and then mapping that to your model.
Oh one other thing, you need to select "texface" in the material tab for the paintwork to show in a render.
Hope that helps.
Greenlig
Blender3D - GIMP - WINXP - DBPro