That's ok, you gave me exactly what i needed :)

I will be using max's bezier curves. There are already a number of scripts for reconstructing a spline with a chosen number of points, so "syncing" the used splines shouldn't be the problem... more the interpolation of vertex positions inbetween... not exactly sure how this is done math-wise though. That's why I needed some references.
I think I'm gonna code some modules. one for syncing up the splines outputting a number of values for the position of each start/end-point, one for making a poly plane and making it editable on a sub-object level, and one for placing the outer vertices on the positions found in the first module, and then interpolating the rest into position. Two of those are a breeze (theoretically) the last one though... :S
Closed spline sweeping will come later :P