Getting GtkD to work on OSX

[Mike McKee via Digitalmars-d-learn]

I have GtkD working just fine on Ubuntu Linux. Now I'm trying to 
get it to work on my Mac with the same hello.d codebase and 
hello.glade file. (Demo here: 
http://stackoverflow.com/a/32535987/105539) What's the procedure 
to getting GtkD installed on OSX?