How do you unzip very large files in python?

Using python 2.4 and the built-in ZipFile library, I cannot read very large zip files (greater than 1 or 2 GB) because it wants to store the entire contents of the uncompressed file in memory. Is there another way to do this (either with a third-party library or some other hack), or must I "shell out" and unzip it that way (which isn't as cross-platform, obviously).