Hi
I'll try to clarify a couple of things here to prevent misunderstandings.
Fist, 25XX-series is strictly layer2 device. That means there's no way you can create access lists with that, you can control IP broadcasts but that's it.
41XX-series does understand some layer3 features like you can create 16 static routes, but no ACLs there either.
What you can do, as advised already, is create port-based VLANs. You can configure each VLAN to a separate subnet. Also you can control on how many MAC addresses the switch will learn on a port.
If you truly want to be able to control things with ACLs, you need a router or a routing switch. In HP range this is currently limited to 53XX and 93XX-series.
Check the management and configuration guides, they're indeed very comprehensive things.
HTH,
Arimo