EDIT:
temporarily unthwarted, got a gizmo that kinda works on the Altera JTAG.
(but not with the Altera Quartus IDE yet)
Must forge some 'USB identification papers' for the thing I think.
Using openocd at the moment. (built in pun in the name!)
Also discovered that KnC made it trivial to do JTAG interfaces WITH the BBB.
('might only' require a cable from one end of PCB to other)
Thx KnCMiner!
The bar is kinda high for my skillset but I blunder on!
Prolly another instance of,
'tolip opens mouth, changes feet'