Can I mount an external NTFS drive as writable when running the install DVD?
I figured it out:

I opened a terminal window and executed mount_ntfs similar to this:

mount_ntfs -s -o rw /dev/diskXsY /Volumes/SomeMountDirectory


where:


-o rw is the crucial part and means use the readwrite option;
-s means mount case sensitive;
/dev/diskXsY represents the actual partition to mount (in my case /dev/disk8s5);
/Volumes/SomeMountDirectory represents the mount point.