The e2tools command line utilities should work just fine on OSX. I'm surprised no one has bothered to make OSXFUSE work with an ext3/4 driver, but it should be

The e2tools command line utilities should work just fine on OSX. I'm surprised no one has bothered to make OSXFUSE work with an ext3/4 driver, but it should be pretty simple. The libext2fs library which ships with e2fsprogs is pretty easy to make work with userspace applications. The the e2tools package uses libext2fs, and there have been FUSE drivers which use libext2fs. I can ask around see if there are some FUSE developers who could update an ext2/3/4 driver that works with OSX and Windows.