I don`t have time to format everything correctly, but here is a working how-to: have fun flashing with your mac
System Information:
Mac OS X 10.7, 64-bit mode
just replace tom with your username, and copy / paste the commands to terminal
Installation steps, problems and solutions
1 download and install macports
2 install a few ports and wait a looooong time

sudo port install pkgconfig libusb git
3 removing old files
sudo rm -rf /Users/tom/Desktop/heimdall/
sudo rm -rf /System/Library/Extensions/heimdall.kext
sudo rm -rf /usr/bin/heimdall
sudo rm -rf /usr/local/bin/heimdall
4 clone git repo
download and install X11
git clone
https://github.com/Benjamin-Dobell/Heimdall.git /Users/tom/Desktop/heimdall/
5 installing libusb
already did that in step 2
6 installing libpit
cd /Users/tom/Desktop/heimdall/libpit/
sudo ./configure
sudo make
sudo make install
cd ..
7 installing heimdall
cd /Users/tom/Desktop/heimdall/heimdall/
sudo ./configure
sudo make
sudo make install
cd ..
cd /Users/tom/Desktop/heimdall/OSX
sudo cp -R heimdall.kext /System/Library/Extensions
sudo chmod -R 755 /System/Library/Extensions/heimdall.kext
sudo chown -R root:wheel /System/Library/Extensions/heimdall.kext
sudo kextload /System/Library/Extensions/heimdall.kext
8 use heimdall
heimdall --help
examples
heimdall flash --kernel zImage
heimdall flash --modem modem.bin
heimdall flash --factoryfs factoryfs.img --cache cache.img --param param.lfs --kernel zImage --primary-boot boot.bin --secondary-boot Sbl.bin --modem modem.bin --hidden hidden.img
EDIT:
oh yes, and the heimdall thread is here:
http://forum.xda-developers.com/showthread.php?t=755265
I wouldn`t recommend using the gui version, command line through terminal is more up to date and has less bugs, working very well for me