This is what worked for me. I downloaded Mono MRE from http://download.mono-project.com/archive/3.8.0/macos-10-x86/.
The latest 3.10.0 version has problems, there are some bug reports about the error -- "Could not execute: GdipCreateFromContext_macosx" which I was getting. Run the installer for Mono 3.8 version which doesn't have this bug. I couldn't not get 3.10 to work at all with IronAHK on my Maverick's version of the OS.
You may need to install xquartz and xcode if they're not already installed (xcode is available from the app store, I believe). info about xquartz is in the other answer. I'm not 100% sure they're required, but they may be.
Next download and extract the latest release zip file for IronAhk from github.com/polyethene/IronAHK/releases . The "site" is only a github repo, so not much to see there and very little documentation. The setup.sh file inside the extracted archive didn't work for me, so I needed to use the make files.
I opened a terminal and changed to the directory of the extracted files and typed:
make
and after that completed (ignored some warnings about unreachable code), I typed:
sudo make install
That installed ironahk to /usr/bin/ironahk
You can try running it by changing to the IronAHK directory inside the extracted files trying
ironahk Example.ahk
If you see a popup window then it works. I got an error and had to set an environment variable for it to work before calling the program.
So this worked for me:
LD_LIBRARY_PATH=/Library/Frameworks/Mono.framework/Versions/current/lib ironahk Example.ahk
PS. This ran the example script, but I got some problems running some scripts that used keyboard hotkeys. I believe the MacOS security model for programs that intercept keyboard input has changed, so perhaps it will be difficult to get running. The last update to this program (as of now) was 2010, so this seems to be a fairly dead project.