[LAU] MIDI over serial port

Hi, I have a somewhat older synthesizer that, in addition to the regular MIDI in/out/thru ports, also has a serial connector (labeled "TO HOST"). Now I'd like to use this serial connection to connect the synthesizer to my Laptop. This gets a little more complicated by the fact that the Laptop does not have an actual serial port, so I'm using an additional USB/Serial adapter in between. What driver or tools do I need to get this combination to work? For serial MIDI there's the snd-serial-u16550 module, but as far as I can tell it only works for "real" serial ports. I've also seen a snd- serialmidi module mentioned a couple of times, but it seems to have been removed from the kernel years ago. Any other ideas? Thanks, Dominic