The mystery settings that gave me direct printing access to the Ricoh Aficio MP C300SR printer have, I think, been rediscovered and will now be documented! This is for macOS Sierra, but it probably works for similar operating systems (at least macOS operating systems).

Add a new printer, as usual, and use IP address 172.17.128.40. Here’s the important, subtle step: select Line Printer Daemon - LPD as the Protocol. The driver software should be found automatically, but if it isn’t, it can be found here.

This is a local IP address and only supports printing while connected to the Saint Martin’s server. It’s much more convenient and feature-rich to use this direct printing method instead of the “web print” method, which only allows certain file types, a maximum number of pages, and clunky interface.

I haven’t gone through the trouble to determine which types of paper are loaded into the alternate trays, but it might be worth doing and specifying those settings.