Note: the technical details are documented on the D-PHYS projects page.
Please have a look at http://wiki.phys.ethz.ch/readme/setting_up_a_new_d-phys-ubuntu_1204_linux_workstation
Login to the LTSP Server
Change the directory where the config files are
Add the host with MAC address and the client settings (Windows login, German keyboard, screen resolution)
Activate the config file
dphys-config -f lts
Don't forget to set the default printer for the client, it works the same way as with the workstations.
Make sure you setup the host to netboot at MacAdm