I'm working on a short Steampunk-themed film and want to do a matte or 3D set extension that combines my two actors on a grassy hill in the forground and a large fortress on the top of the hill.  We're shooting the scene at a nearby farm with a nice, hilly pasture.  What would be the best method of creating a sloped, grassy area around the Poser building?  I need a groundplane that can be morphed and minipulated to create hills and a good grass texture to put over it.  I've done lots of Poser animation and combined the figures with live actors, but I've never tried to create a scene with a realistic landscape.  Some of Flink's stuff here at Renderousity looks like it might work, but I'm unsure if you can morph the ground on his grassy meadow.

I know Vue might be a better option, but this shot has to move in 3D space and I don't have three weeks to render a single scene.