Fwiw I just tested a (different) USB keyboard with the quantal server image from 2012-09-21 on a Mac Mini 5,2 and it worked fine for selecting the language and starting the install.
Fwiw I just tested a (different) USB keyboard with the quantal server image from 2012-09-21 on a Mac Mini 5,2 and it worked fine for selecting the language and starting the install.