A simple script I wrote, based on Alan Fregtman evenCurves.py
I still need to work a little more on it. Depending on the selection order it won't work properly.
The process is quite simple, without complex maths.
It's basically extract edges as curve, rearrange the curve with even spaces and align the points of the original edge selection to this curve.
It seems to work now with closed edge loops too. It still needs more work but for now it seems to do the job more than less. It may be a little slow on very high meshes.
The file above is a plugin file. Copy it into your \Application\Plugins inside your Softimage user folder or Softimage Workgroup folder.