Nobody does a 'mount -a' on the player -- the disks are initially mounted by our init, and then unmounted/mounted by the player directly. The rw and rwm scripts are for convenience -- nothing usually runs them. So:

You need to mount the disk explicitly (not with -a) in preinit (equiv of init), and modify the rw and rwm scripts for your convenience. The player should ignore your partition with this scheme -- which is what you want.