/dev/hd0 is the raw hard drive, and /dev/hd0t180 is the raw partition. Neither of these is a mount point where you can view files. The reason /dev/hd0t180 has t180 as the suffix is that in the partition table of /dev/hd0, the partition type is 180. If you really want to change this, which I’m not sure of, you can use fdisk to carefully change just the partition type. Once you do this, you could reboot, or instead:
umount /dev/hd0t180
mount -e /dev/hd0
After this, the new partition will show up.
Now if you want to see a mount point, you might find it in /fs after you reboot.
If not, you can mount the partition yourself as:
mount -t qnx4 /dev/hd0t180 /hdd0
I would not put these in rc.sysinit, rc.local is a better place.
But I wouldn’t update either file until I figured out how to do it successfully from the command line first.
If this is not the boot drive, and you don’t want a partition on it, it is possible to
“dinit” /dev/hdd0, and mount it the way you indicate in your post, but this is rather unorthodox. Forgetting the partition table is usually done with floppy disks, and some removable media.