How to create an abstract looking skybox??

Hi, Im really new at this but was wondering how I might be able to create a somewhat abstract looking skybox. If you know the game LIMBO - the look of the background and sky is what im trying to achieve.

how do you make sure that the 6 images line up - is this possible??

Any help would be most appreciated!

Skyboxes will align themselves up, you just need to provide the textures.