Thanks for your explanations Michael. What I need to do in the end will be a hiking boot very much like this:
http://upload.ecvv.com/upload/Product/20095/China_Men_Hiking_Shoes20095182102462.jpg

The 3D model of the predecessor was made with rhino. So I thought it would also be possible with MOI...
I cannot come up with a plan to make it without spline patching. Is there a better and simpler way?

Cheers,
Rogurt