There's no easy way to do this in 2.x... Unity 3.x has support for 10 MWI lamp codes for each subscriber. You can even get real fancy and have it light lamps on different phone switches with different codes using multiple MWI defintions in your switch file if you really want to.
If you're desperate and you really can't get off 2.4.5 you could hack it and use a pager notification device, for instance, to send a dialable lamp code (assuming you have analog lamp codes at your disposal... wont work for digital or serial integrations).
the only other way I can think of would be to create a series of dummy subscribers and have messages left for all of them when you leave a message for subscriber X and each of these dummy subs would have a different lamp code. There weren't per seat license charges in 2.4.5 so this wont cost you any money but it is a headache to setup and maintain if you want to do this for a bunch of folks.
Are you getting this error “Installer User Interface Mode Not Supported. The installer cannot run in this UI mode. To specify the interface mode, use the -i command-line option, followed by the UI mode identifier. The value UI mode identifiers...
The below trick might come handy when you have to add a new node to a cluster but you don't have or is unsure of the security password for the publisher. This procedure has been around for ages.
1) Login into the CLI of the Publisher.