Well I tried the one on rhinotv (a Sedan model) ... and it was just impossible to follow, there are too many missing tools.
The main one are :

Continuity (at least G1) when creating 2 rails sweep surface.
Continuity when creating network surface.

There are also using a 'fair' tool (not really sure what it is, some kind of smoothing curve command ?), and many rebuild tool (surface / curve) ...
So I give up after the first network surface :(

I know MoI toolset wasn't focused in this area, but I realllly hope this kind of tool (especially the continuity stuffs) will appear soon :)
Top priority for me (with a patch tool and a more advanced surface blending one that allow multicurve) , ... it's even more important (for me) than the object layers management.