Writable NTFS on Yosemite

Remove osxfuse if installed via homebrew:

brew uninstall osxfuse

Install osxfuse binary and choose to install the MacFUSE compatibility layer

Reboot (optional but recommended by osxfuse)

Install ntfs-3g via homebrew:

brew update && brew install ntfs-3g

Link mount_ntfs:

sudo mv /sbin/mount_ntfs /sbin/mount_ntfs.original
sudo ln -s /usr/local/Cellar/ntfs-3g/2014.2.15/sbin/mount_ntfs /sbin/mount_ntfs

Reboot