this isn't a very easy task, but it isn't too difficult eighter. all you have to do it:
compare the walls with the wall-format (don't ask how it looks like, just go to the gfx-board and have a look at the "example-graphics"-thread!), remove or add single pixles where necessary etc.
further, there always have to be 2 walls from 1 image (northern and southern wall...).
who thinks he is able to handle this? (it needs some kind of... well, brain

martin