UnwrapUVW planar projection w ratio 1:1

Hey Guys,

I just started writing a script, I usually write just one script a year when its really necessary, so I'm really not a pro, and pretty slow at it so be easy on me :).

Here's the deal:
I've just imported a big scene in 3Ds max of a small Belgian town with V-roof houses. The scene is really low poly. I wrote a script to make an aligned planar projected map for every single polygon. (using unwrap_UVW) So far so good, but now I need this planar mapping to be a 1:1 ratio but also to have a set scale for all polygons.

Does anybody have an idea how I could be fixing this?

Thanks all!