Samsung ML 1665
A driver for this printer is not included in the default library of printer drivers. However, Splix project (http://splix.ap2c.org/) provides CUPS drivers for SPL printers.
1. Splix is available in portage, so you simply need to emerge it.
Refer to the generic installation instructions for CUPS/your desktop environment to finish setting up your printer. When asked about printer model, simply select ML-1660 series and you're done.