After hearing a lot about problems with installing gretl on OS
X 10.8 I managed to borrow a current MacBook Pro from a
student and have walked through the installation process
myself (the machine had no previous gretl installation and no
XQuartz or GTK).
It went fine, although some aspects of the operation were
potentially confusing (in particular the way that new disk
image windows open _behind_ the Safari window so it kind if
looks like nothing has happened unless you minimize the
browser).
Anyway, I wrote up some detailed blow-by-blow instructions,
which I'm attaching. If any Mac users have points to add or
correct, please let me know. Then I'll put the instructions on
the website in some form.
Allin