Attached is the addition of the 'low_level' parameter to ZipFile. Included are the parameter, a global switch controlling whether the parameter will raise an Exception or trigger a DeprecationWarning (the latter, for now), updated tests and updated documents. I didn't run test_zipfile64, I can't say for sure it works but I have no reason to believe it doesn't.
Changes are against py3k; let me know what you think, I'll backport to trunk.