Good news, everyone: I've finally had some luck with getting HoustonTracker to work with TI-OS 19.006.
Let me explain. ROM 19.006 is the OS version used on the "CS" and "Parcus" models. Those are belated versions of the 82 with a different case design. Most notoriously, the Parcus was dumped by TI mainly on European markets in 2001, two years after the 83+ had been released. Unsurprisingly, it flopped completely. Which is why you can find truckloads of them on Ebay.
Got my Parcus from the Bay for a few bucks about a year ago, still in it's glorious throwaway plastic packaging. So far I've had nothing but trouble with it (aside from the fact that it's made of really cheap plastic and looks totally ugly). There's near zero documentation on it online. The "great" new sideways link port is a far stretch from the tightly fitting 82 ports, and it doesn't work with my home-made parallel link most of the time. And worst of all, Texas Beeper Massacre doesn't run on it, because the display driver runs at the wrong speed.
But now, thanks to my new SilverLink, I can at least communicate with the calc. Well, more or less reliably that is, sometimes I have to "massage" the link port a bit. Well, makes sense now that that book is called "The Medium is the Massage". But I digress.
Today, I finally managed to load a build of HoustonTracker that didn't crash immediately... Yeeehaaaww!
Sound doesn't work yet, though. This confirms something I've been suspecting for a while - port addressing has changed in ROM 19.006. Probably it'll be using 83-style values ($d0..$d3 or what was it). Will check that in the next few days.
So, long story short, there is hope for all those out there who are unfortunate enough to posess one of these atrocious pieces of TI hardware. To all those who don't have one yet, my advice remains: Stay clear of them, they're crap. /rant