This is a copied, exported repository from original one hosted on Google Code. Also see SIMBL web site.
master
branch contains a few changes to make it works with current OS X and Xcode.
Use xcodebuild to get SIMBL.osax
, then open pkg/SIMBL.pmdoc
by PackageMaker to build pkg file.
xcodebuild -project SIMBL.xcodeproj
You can still download PackageMaker from Apple's download page as a part of Auxiliary Tools for Xcode - Late July 2012.