I'm actually at another location, but at another laptop also with Vector Linux 5.9 installed, and I've got mysql working!
I followed all the steps you listed and finally got to the mysql> prompt. Now I have to learn how to use it!
Lost it again when I rebooted, but recovered it again by following the relevant steps. Now have to set it up so that it is available via VASMCC.
Hopefully, it'll work on the other VL 5.9 machine, when I get back to it on Thursday.
Many thanks for all your dogged help! I'll wait until I've got the other machine working OK before I mark this 'SOLVED'.