Hi ed,

re:
> Hi there! is there something in MoI similar to tween curves in Rhino?

You can get the same kind of result by making a Loft between the curves, and then using Construct > Curve > Iso to extract some isocurves from the surface.

Max also made a plug-in for doing it which you can find here:
http://moi3d.com/forum/index.php?webtag=MOI&msg=6373.1

- Michael