You guys should add, you can also chop up a normal picture and completely replace it without using that template.
if you load it in texture/loading/space you can add:
space_back_left_bottom.dds (256x256)
space_back_left_center_bottom.dds (256x256)
space_back_right_center_bottom.dds (256x256)
space_back_right_bottom.dds (256x256)
space_back_left_top.dds (512x512)
space_back_right_top.dds (512x512)

This gives the emu team load options, as well as easier submission options. Basically make a 2048x2048 and chop it into 6 pieces 4 256x256 pieces on the bottom and 2 512x512 pieces on the top for the whole image. (Credit to Himilayas for pointing this out to me months ago)