That's how I did that in the early 90's. OrCad SDT and Word for DOS. But now? Eagle doesn't even have a native HPGL output format :-(
Maybe it's not needed much anymore. One of the main reasons were early laser printers. My first one could not take more than 1MB in additional memory and even that cost a bundle. Barely enough for a dense schematic. But since it was an HP it understood HPGL perfectly well and printed marvelous schematics from that. The newest printer here in the office has oodles of memory. It can store a big fat stack of pages and print it all out later.