Hi and a happy new year!

i use for terain IceX2.0! A tool for that what you want, trust me!

you can add mdl´s at runntime!
you can texture at runtime the terain!(your own texture´S)
you can scale at runtime the texture!

...i love it!

here is a link!

hope that help you! ps: my eng is not so very good (im german)!

-jack