Just figured it out -- need to use the diskutil command, e.g. in a terminal window do the following
diskutil rename /dev/disk8s2 MacOSX_10.5
and it changes the name and remounts it as /Volumes/MacOSX_10.5
I found the diskutil command while looking at...
Does anyone know how Mac OS X 10.5 (Leopard) figures out the mount points for the volumes on the system? I added a new drive and cloned the old boot volume to it and I want it to mount with a different name than what Disk Utility chose for it. The old boot volume was mounted as "/Volumes/Boot"...