Can you give us some output of errors that you're getting when you try to build the toolchain in OS X 10.7? We can use the info to make a few fixes.
Also, and this may be not too relevant... are you using the latest Xcode version? IIRC it's 4.1 currently. As far as I remember, us Mac users need to have Xcode installed beforehand to do any kind of software building.