There is no need to compile anything since the whole program is just a Python script. Just run it, and that's all.
PySol requires Python 1.5.2 and Tcl/Tk 8.0.5 or better. Both packages are freely available for Unix, Windows and Macintosh platforms.
PySol is free Open Source software distributed under the terms of the GNU GPL.
If you want to modify the PySol source code or write your own Python programs you can get the development system from http://www.python.org/download/download_windows.html
Also, installable packages exist for all major Linux distributions, FreeBSD and HPUX.
As I don't have access to a Mac I'd appreciate any detailed feedback on installation and look & feel. "Porting" from X11 to Windows only required some minor changes in the default font settings, so I hope the situation on Macs is similar.
[ I have been told that PySol works fine on a Mac - just drop "pysol.py" on the Python interpreter and that's it. But for some reason you must assign a large amount of memory to the Python interpreter. ]