I do development on Mac OS X. I have a user who is contributing code with CRLF line endings. He currently does not use git. I create a branch, then switch my working tree to it.
I think, you can try new (1.7.2+) core.eol
Sets the line ending type to use in the working directory for files that have the text property set. Alternatives are 'lf', 'crlf' and 'native', which uses the platform's native line ending. The default value is native
And don't use buggy and not-obvious core.autocrlf