Installing two QNXes on one HDD (one physical disk)

I’ve got 80GB hdd with 4 primary partitions on it:

partition #1 (type 79) QNX 6.3 SP2
partition #2 FAT32
partition #3 NTFS
partition #4 unused

I want to install QNX 6.3 SP3 on partition #4 (like on part. #1),
but the installer force me to choose part. type 78.
Why it can be type 79 ? (like part. #1)

Now, after every reboot I have to choose
file system mount point.
Why QNX don’t mount file system from active partition automatically?

Because some people asked why the loader didn’t allow user to select booting from another device…

can I automatize this process ?
/can I choose it (root partition) in some conf file ?