Or... "I flew my C-Plane into the Orient Express!"
After a year of using MoI - one of the simplest 3D modelers in the world - there are possibly a few tools that still allude me.
No, I can believe it myself.... It's not that I can't make them work, it's just that I've so rarely had to use them, I feign to push the button for one reason or another.
The very useful C-Plane tools is one of them. First, it's icon resides in a command panel I rarely ever access.
Second, the Orient tools lump together with C-Plane in my mind. They are all siblings of each other - and I'm having a hard time getting that three-lined "gumball" widget to do what I think it looks like it's supposed to do.
But I do know (somewhat) what these
re-orienting tools can do for the MoI modeler:
In the MoI Resource section in the Command Reference
http://moi3d.com/2.0/docs/moi_command_reference.htm
You'll find description for each:

C-Plane
http://moi3d.com/2.0/docs/moi_command_reference5.htm#cplane
The C-Plane tool will align to an object or construction line and re-orient the C-Plane grid so that the area of your choosing on your model will now be perfectly lined up with the grid as if you constructed it there.

Orient
http://moi3d.com/2.0/docs/moi_command_reference8.htm#orient
The Orient tool will align selected object themselves to orientations related to objects or construction lines in your model.

Line-To-Line
http://moi3d.com/2.0/docs/moi_command_reference8.htm#orientlinetoline
The Orient Line-To-Line tool will take a curve and magically stretch and reposition it to a target curve, connecting the sets of two end points together.

View-To-View
http://moi3d.com/2.0/docs/moi_command_reference8.htm#orientviewtoview
The View-To-View tool "Remaps objects from one view to another view." Okay, never tried it (successfully) it has to be cool, right?
Michael, I would be grateful if you could please elaborate a little on these functions. I can now think of dozens of time where even C-Plane could have saved time.
This file is a part of a model that is part of a larger model, so the need to cut a circular array of the "scoop" object not aligned to x,y or z would be nice.
I think I have the hang of it, except for what happens when you start moving the white ball around and you change the Z orientation.
Nothing like a little disorientation to add spice to a model.
http://k4icy.50webs.com/tutorials/to_orient_ex_01.3dm