Hmmm.... In my experience the most common form is
"Well, if the mountain
won't come to Mohammed..." meaning "very well, I'll do it myself",
I'm not
sure how the other way round would work. "Well, if Mohammed won't go to the
mountain..." meaning, "very well, I'll do it for you" doesn't make
much
sense (given that a mountain is unmovable...). Or perhaps you meant some
other usage.
That's pretty much the usage I had in mind. It's a figure of speech,
it doesn't have to make sense.