Please see my comment to the question. Sorry that I don't know the complete answer, but I'll tell you where to look for. I used to use Mono on Mac OS X, and I know that Mono itself won't be enough. You need to get access to Mac OS X specific API, in particular, Cocoa. So, you will need Monobjc on top of Mono:
https://en.wikipedia.org/wiki/Monobjc[
^],
http://www.monobjc.net/[
^].
Note that you will have to start your Mono application not through Mono commands (Mono application_file_name), but through equivalent monobjc commands, which are exactly the same as in Mono.
See also:
http://www.murgaa.com/mac-auto-mouse-click[
^].
—SA