This is what I had to do to compile the code on a PPC Mac OSX 10.4. (It should be the same for 10.3)

The easiest way to get the code dependencies (gsl, cfitsio, fftw) is to use one of the 3rd party package managers
available for OSX. Two that I know of are DarwinPorts and Fink. I have also been told, but can't directly confirm,
that there is not yet a free F77 compiler for Intel Macs. If this is not true, please let me know.

These instructions use DarwinPorts, which requires administrative privileges and assumes you have a C and F77 compiler.
DarwinPorts installs stuff into the base directory /opt/local/. Fink installs stuff into the base directory /sw,
so if you use Fink, you will need to change the first INCLUDES and LIBS at the top of Makefile.osx

1- Install DarwinPorts package.
go to http://darwinports.opendarwin.org/ get darwinports and do the default install.

2- open a terminal window, type:
sudo port install fftw
(this takes about 1 min)
sudo port install gsl
(this takes about 10 mins)
sudo port install cfitsio
(this takes a while. It required gcc 3.4 to be created on my machine. Not sure why, but it all worked.)

3- untar the lensview tarball. change the line in lv_image.c (around line 26)
#include "rfftw.h"
to
#include "drfftw.h"

(This is because the default install from darwinports includes only the double-precision library.
If you know how to get port to build both, please tell me.)

4- get fastell.f and dependencies as per the main webpage.

5- make -f Makefile.osx lensview