Firstly, thank you for the extremely thorough walkthrough. You are the absolute MAN! It would have been very easy of you to simply say, "Use Portmaster, look it up," but you didn't. As thanks, be on the lookout for my purchase of WTC+. Think of it as a tip not only for your help in this matter, but as recompense for the hours of enjoyment I've gotten from your various pico8 titles (the original WTC is a personal favorite that I recommend often). Take it to go get yourself a Red Bull or a thirstbuster or something.
That said, I'd hoped my solution was vastly more simple: put the files into a folder I hadn't thought to use, or add an appropriate extension to the whiplashtaxi file and it would magically run itself…something I could wrap my clueless head around. Don't get me wrong, I'll attempt to get it working following your instructions, but I'm not gonna hold my own breath that I'll figure it out. (For the "bash script" above, I just copy/paste to a text file then change its extension to .sh, correct? Told you…clueless.)
Anyway, thanks again for taking the time, for being truly helpful when others may have been dismissive, and for the enjoyment you've provided through your other titles.