Monkey Patching, passing in extra data, FXRuby bug

Because of an apparent bug in FXRuby/Fox/Something that causes a
segmentation fault …

I am looking for a workaround to a problem.

FXRuby defines a class FXTreeItem.

That class has an instance method for the spaceship operator … <=>

And the spaceship operator is called by FXTreeList to sort the child
node of the Tree for display.

What I want to do is monkey patch the spaceship operator with my own
spaceship operator … but I need to pass in extra information so that I
can force the proper sorting order. I don’t control how FXTreeList
calls the the spaceship operator.

I would be grateful for suggestions on how to do this the Ruby way.