gWiiLoader is a simple frontend to wiiload made using Python.
It requires Python 2.6 , GTK+, and PyGTK, which are all included on modern Linux distributions. It is very likely that it will work on MacOS X as well, though GTK+ and PyGTK would have to be installed manually. It has not been tested at all with MacOS, so you're on your own there.
Either place wiiload in your path, /usr/local/bin/wiiload is recommended, or place it in the same directory as gWiiLoader. Then run gWiiLoader. Put your Wii's IP in the box, select your app, and hit Send. There's no feedback on success or failure, so if you select a bogus .dol or .elf, or wiiload gives some other kind of error, you'll only see it in the console. This is a quick n' dirty GUI, nothing more.