I needed to brush up on my plotter-design skills. Turns out it's harder than you might think to make stuff look good on the plotter. This one turned out OK.
For anyone out there who would like to do the same thing I have been doing with my plotter, there are a few things you should know. These old plotters are generally inexpensive and fairly easy to obtain, but you won't find drivers for Windows or Linux or Mac OSX anywhere on the web. That's because these plotters don't actually require drivers to run. You just need to know how they work and it'll make perfect sense.
Most old plotters will be HPGL standard plotters. All HP and Roland models will be HPGL, and many others will be too. An HPGL file consists of simple commands stored in a text file. Inkscape can generate an .HPGL file from an SVG drawing by picking HPGL output from the save dialog box. Once you have your file you can send it to the plotter with a normal terminal program. Since I use Linux I chose Minicom, but in Windows you could use HyperTerminal. Just make sure to have the correct baud rate, bit rate, and handshaking mode set, then start an ASCII file transfer. Pick your HPGL file and your plotter will be on its merry way.