Finally got the 5ADV firmware sorted out, it was a real nightmare to work on because I threw everything possible against myself.
The chip has to be programmed at 5V but I put it into a 2.48V circuit, the programming pins don't like any sort of load on them (during programming) but I put my buzzer and LED on those two pins [ remember, there's only 3 usable pins on this thing ]. The circuit board itself has no provision for programming pads so I had to jig it all together with fine 30AWG single-strand wire and try not move it too much (else they break of course). Finally, it had to be coded in Assembly... because the chip is so tiny it cannot handle the sort of firmware that would be generated from C (yet).
Good to have it working now... my wife is duly irritated at the "Damned beeping"