Putting the printer into HPGL mode with the correct PCL sequence instruction, lets you control the printer (very inefficiently) directly from within something like QBASIC, just by writing some simple human-readable words to the LPT port.
You can make polygons, lines, fills, fancy text, and all that snazz, with just a subset of what HPGL offers. You can even make "stipple" patterns-- (laserjet printers have an absurdly small "Pen size" by default though, so the dots are super tiny. This may or may not be desirable, depending on what you are trying to do. If you want to make a program that does custom halftone and moire pattern effect, for instance, it might be fun to have a tiny pen size. But for any actual "use", like making/printing documents, the fill commands are vastly superior.)
It only takes a single instruction sent to the vintage laserjet to put it into that mode (or take it out again). A very small DOS program could be made to do it "with very minimal effort."
HPGL is, however, "Very klunky", due to its nature. It would take a long time to send a full page's data to the printer's built in print buffer. (Unlike a vintage plotter, which is what HPGL is actually FOR, these laser printers aggregate the full page's instructions, then execute them on the "page feed" instruction. Vintage plotters perform the instructions "Immediately". You can push the pen around in fun ways using that ability.)