Thanks for the answers!

I thought about the SDK solution - but the engine didn't load the included dll. Perhaps I don't know how to handle with plugins or it's the fact, that I use the LiteC Free Version. I really don't know. I have also read the manual about SDK.

After that I tried the ent_clone function. Ent_Clone function works with SED but if I use the C# Wrapper the engine throws an error 'E2005 - Can't create DirectX texture mtl_shaded.' Did I forget to implement some shaders?

Indeed the easiest solution would be to create an own wmb file for every tile . But I think this solution isn't felxible enough for the user. It would take a lot of time to create them.

I will go on and try to solve the problem with ent_clone.

Nevertheless, I would appreciate further help. =)
Regards Marco.