Well, yes; AAMOF, it is based, somewhat, on my OS of choice: FreeBSD.
However, the filesystem layout, the GUI, and the method of installation of various things are not "FreeBSD standard", so I'm not sure I can tell you want to do.
In FreeBSD, if PEAR isn't installed, it's as simple as (if you have root perms, that is 😉 ) :
$cd /usr/ports/devel/pear
$make install clean
I'm not sure I can tell you what to do on Mac, though; as another example of my "Mac stupid", I went to install Adobe's PDF reader on the same class Mac after I found the power button; although I could find the install file on the CD I'd burned, I couldn't figure how to run it to install.
Basically, since it's just a charity job anyway, I'm letting it sit over there until somebody else tells me how, heh, heh....