currently you don't have a lot of good options for installing large numbers of desktops. VMO can be deployed using tools like SMS but most folks don't care to tangle with that. Some sites have just stuck the VMO setup on a shared drive and emailed out a link to it for everyone. The only thing users need to know when installing it is the Unity server name (or IP address) and the extension number of their phone if they're using TRAP.
In Coppola (4.0 later this year) the VMO stuff will be bundled into a snappy MSI package that can be scripted, support group policies and all that good stuff. This'll make large deployments and updates much, much easier moving forward.
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.