You have two topics about this , TheBadger. I thought this is the better place .
It can be done. But i would do it as an object if you ask me.
It has problems but planed accordingly you could use it anyway.
I did put two TGD files in the " Projects.7z " attachment file
(below here in this post). One with a merger shader , the other without.
If you or anyone want to make better nodes etc. feel free. There are many ways probably.
For example i used 3 surface shaders ; You could use less (it works too).
Do not read too much in the settings. I made this very quickly only to test if this works.
There could be checked places i didn't wanted to check etc.
The "The_Wall_Tests..." picture
( look at the next post below) :
1 : I tried to merge the X and Z wall side textures but could not do it properly with this method .
(The walls are not smooth because i made a very basic mask very fast . So please do not take it into consideration. )
2 : This is much better but you have to plan and make the masks accordingly.
I only partially made some changes you see here marked .The mask is a little different. For the X and Z side.
3 : Texture only on "Projection type : Side X" .
4 : Texture only on "Projection type : Side Z" .
Maybe if Planetside (or some of the node-math wizards here
) would put kind of a "Cubic Mapping"(if possible) option most of this could be done more easier.
I tried the LWO exporter . It has his own problems (polygon heavy for better object) but i would use this (with Poseray(free) you can convert it to Obj ).
But everyone has his own work flow and programs of course .
Hope this is any use for you or others.
Cheers