specifying root / adding a hard disk

Hi!

my SS4 is tight on disk space. The internal Hard disk is SCSI Target 3, 
pretty standard!

Now I want to attach an external hard disk I use on the IPC, I could use 
and add the swap partition.

Actually i could even then try to install 9.4 on it externally and do 
some tests...

External disk is set to Target 5, but probe-scsi sees it as target 0. 
Even if I change it to 4, it still things it is Target 0, maybe it is 
broken or not connected.
Anyway, if I boot of disk (remember, 3) it works, but then internal disk 
gets sd1 and not sd0, so NetBSD is confused and tries to mount the other 
disk as root and dies.

I need sd0 to stay sd0 :) Or to say somehow sd1 is boot root for this test.

The only way would be to set (and have it recognized) an SCSI ID > 3 I 
suppose?

Riccardo