I just went through a bit of a hassle, but eventually think I found out which spells you'll have to cast.
- Make sure you're on the math network and turn off any HTTPS-enforcing plugins in your browser. Go to http://www.math.tu-berlin.de/iuk/forschungsrechnerbereich/service/drucken/cups-server/ to see the full list of available printers. The room number is part of the printer names, so you should be able to figure out which one you're targeting. Write down the printer name and the server url (e.g., ps43.math.tu-berlin.de).
- Open a browser, go to the CUPS interface at http://localhost:631/. Click Administration->Add printer.
- The list of printers that are presented to you means nothing. Choose "Internet Printing Protocol (IPP)".
- In the "Connection" field, fill in "ipp://<server url>:631/printers/<printer name>" where you take <server url> and <printer name> from above, e.g., ipp://ps43.math.tu-berlin.de:631/printers/p465d.
- When asked for a driver, fill in one of the drivers that seem appropriate, e.g., "HP LaserJet 4300 - CUPS+Gutenprint v5.2.9" for an HP LaserJet 4300 printer.