I forgot, here's the bat file and some info:
Terragen.exe -p "path\jap.tgd" -o "n.bmp" -r -rendernode "n"
Terragen.exe -p "path\jap.tgd" -o "e.bmp" -r -rendernode "e"
Terragen.exe -p "path\jap.tgd" -o "w.bmp" -r -rendernode "w"
Terragen.exe -p "path\jap.tgd" -o "s.bmp" -r -rendernode "s"
Terragen.exe -p "path\jap.tgd" -o "up.bmp" -r -rendernode "u"
Terragen.exe -p "path\jap.tgd" -o "dn.bmp" -r -rendernode "d"
Just paste this into a clean bat file and run, make sure you fill in the correct path. For some reason I couldn't do just the file w/o path, but this works as well.
In the scene, create 6 cameras, set each one of them to the correct rotation and make sure the coordinations and quality settings are exactly the same, these are the rotations you need:
N = 0 0 0
E = 0 90 0
W = 0 180 0
S = 0 270 0
UP = 90 0 0
DN = -90 0 0
Then make 6 render nodes, connect each one of them to the corresponding camera, make sure all render nodes have the same quality settings. BTW, cameras and render nodes can't have the same name for some reason, so just name the cameras to something else. In my case I named the cameras the full length name and the render nodes the short version.
Save. Quit. Run the bat file. It will run silently w/o opening the program, you can set it during sleep or whatever.
This is the result, stitched in photoshop. It's a sky for my quake 3 level. This is a shrunk down version, in reality, each image is 1024^2, so it will look very crisp and clear in game.
