How to recreate BIG Battersea Powerstation project?

Hi everybody.. 

I'm trying to figure out how to recreate something like the B.I.G. project for the Battersea Power Station in London. 
I've got a street network (a bunch of curves) and I need to model it in the 3rd dimension, with smooth curves and soft edges: the terrain inside the cells goes down, the streets go up. 
I've found some nice Waver Bird scripts, but I'm not able to adapt those scripts to my needs. Any ideas?

Thanks a lot