There are a lot of options to make ntfs mountable for read and write like ntfs3g, tuxera, paragon but isn't it like rw support worked in some older OSX versions?
How to put drivers from older OSX in Lion (Mountain Lion) to make it read and write to ntfs with native drivers.
I've tried open-sourced packages NTFS-FREE and FUSE for OS X on Mac OS X Mountain Lion v10.8.2 and can read/write NTFS partition successfully, although NTFS-FREE only claimed to support OS X up to v10.7.
You must install both of the following packages to get things work.
FUSE for OS X: http://osxfuse.github.com/
OS X has never supported writing to NTFS formatted volumes out of the box.
By default OS X will always mount NTFS volumes read-only.
