Hi have you tried the warp brush or mesh warp to move the end or part of the ribbon you want to pinch?
I am sorry but this is about the best visual tutorial I can come up with for the mesh warp
http://glhold.com/tut/meshwarpvase/meshvasetut1.html seems everyone mentions and talks about how good it is, but very few show you how to use it.
Here is one for how the warp brush works..
http://campratty.com/8/8pages/8p06b.html
http://campratty.com/8/8pages/8p06.html
They are really easy to use, easy to see what is happening while you are moving your pinched area of the ribbon. hth's a little