I create logical volumes wherever I want (does not have to be in vg00) and add an entry in /etc/fstab
/dev/vg01/dump / dump defaults 0 0
but you can enter
/dev/dsk/c#t#d# / dump detaults 0 0
and do crashconf -arv
Then I make sure that CRASHCONF_REPLACE=1 in /etc/rc.config.d/crashconf and SAVE_PART=1 in /etc/rc.config.d/savecrash.
No reboot required but if you do reboot, it should not revert back to the lvol.
Marlou