The thread I was reading regarding this was last updated 2 years ago. Was this ever a thing?
I believe the “Burning THAC0” threads (at least the ones I’ve seen) were about a long running, “D&D” inspired/styled Burning Wheel campaign and not a publication idea. (You can pretty much “burn” most any type of medieval campaign with the rules in Gold, Historical, Fantasy, Fictional. It’s all good)
I believe it’s also a hack for BW, but a hack that was done in Revised initially. Maybe there was talk of upgrading it?
It was both. I believe Ara (who compiled the guide) has been busy with life since.
Cursory inspection of the document, which can be found at: http://www.burningwheel.org/wiki/index.php?title=Downloads#Burning_THAC0 seems pretty applicable to Gold. Use the usual Monster Burner quick and dirty conversion guidelines (Convert weapon speeds unwieldy, slow, fast to 1, 2, x respectively and Double the speed modifier to get stride) and you should have something workable.
Note that the biggest issue is the conversion of magic spells. Either use BWG spells, or try Art Magic from the Magic Burner, or use Thor’s untested Abstraction/Distillation fix: http://www.burningwheel.org/forum/showthread.php?11438-Using-Abstraction-and-Distillation-with-BWG
I spoke with Ara on Google+ today and he indicated he could proceed with Burning THAC0 Gold if he got the okay from BWHQ. I believe he’d also like some assistance in editing the document.
I need to write these down somewhere.
I wrote it on the inside cover of the MonBu 
That’s a shockingly obvious idea, come to think of it. Nice one!
I’m a neophyte, but I do love me some copyediting. If Ara wants help, I’ll throw my hat in the ring.