Hiya.
A simple cubic map for a humanoid model isn't going to cut it, unfortunatly. A cubic map is just that; a cube. It projects a texture from 6 sides; where these sides 'meet up' is where you will likely see seems. If you really want to just do a 'quick and dirty UV map' for the model, I'd suggest using a cylindrical projection. The inside of the arms/legs will look strange, and the top of the head, but it might be better than cubic.
For a good texure map for a humanoid model, you pretty much have to do 'real' UV maping.