All of the code necessary to build a working Chrome Frame and an installer binary is present in the open source repository. The code for the MSI isn't there, but that's just a very thin wrapper around the Chrome Frame and Google Update exe installers.
If you've got a copy of the MSI already, run it against Dark (the WiX decompiler) and you'll be pretty much handled a copy of the MSI source. Obviously you'll have some cleanup work, but it's a hell of a start. http://wix.sourceforge.net/manual-wix2/dark.htm
Yup it certainly is... too bad that the build is not usable without extensive knowledge of how to integrate it into IE. Something which a very limited subset of people know.
