To get rid of the whole RTools/Apple Xcode mess when installing from source, I compiled binaries for i386/x86_64. This installation process has been tested to work on 32/64-bit machines on MacOS 10.5+ and Windows 7. If somebody could try it out on Vista and XP, that would be much appreciated.
Updated instructions are at http://install.rtexttools.com/ .
Best,
Tim