In order to use the various command line utilities in unreal, you do actually have to build the engine.
It takes a while to do, but it's quite easy.
Go to https://itunes.apple.com/au/app/xcode/id497799835?mt=12, or search the App store.
It's a free install.
Go to https://www.unrealengine.com/ue4-on-github and follow the steps there.
Notice that you must first perform steps 1 and 2, above.
If you want to automate this process using this repository, do this:
git clone git@github.com:shadowmint/unreal-mac-setup.git unreal
cd unreal
sh ./setup.sh
Notice that the build process downloads several GB of data, and compiles hundreds of source files. It might take an hour or so.
Otherwise, follow the steps listed below.
git clone git@github.com:EpicGames/UnrealEngine.git
cd UnrealEngine
sh ./Setup.sh
sh ./GenerateProjectFiles.sh
xcodebuild -workspace UE4.xcworkspace -scheme UE4
Registering git hooks... (this will override existing ones!)
Setting up Mono
Checking dependencies (excluding Win32, Win64, Android)...
Updating dependencies: 99% (20986/20998), 3386.0/3409.3 MiB | 0.00 MiB/s...
...make sure your computer isn't set to 'wake for network access' in the power saving settings.