Searching the internet hasn't yielded much either (my google-fu is weak here) though I've found some vague hints that the switch might not support it at all.
Can anybody give me pointers? (Am I looking all the wrong places? Does the feature have a different name in HP-lingo? Or do I have to buy a new switch to get support?)
Edit: It is to be used in a condominium with ~20 apts, so it's all about protecting the users from malconfigured wifi routers and other idiocies. The switch sit behind a Soekris/PFSense firewall that takes care of NAT/QoS/DHCP.
Edit №2: It all turned out to be fairly simple. After updating the switch firmware (hooray for HP doing free updates 10+ years after initial release!), it's done thusly:
> config > port-isolation Answer ‘y’ > port-isolation e 1-22 mode private > show port-isolation > write memory
Now ports 1-22 (residents) can only talk to port 23/24 (router/debug port).