Ok, so I go it solved, so figured I'd list solution here.
1) Created a file called "additionalGasSensors.py" and placed it in /usr/share/weewx/user (at least that's where it goes on my machine)
import schemas.wview_extended
schema_with_additionalGasSensors = {
'table': schemas.wview_extended.table + [('c2h5oh', 'REAL')] + [('c3h8', 'REAL')] + [('c4h10', 'REAL')] + [('ch4', 'REAL')] + [('h2', 'REAL')],
'day_summaries' : schemas.wview_extended.day_summaries + [('c2h5oh', 'SCALAR')] + [('c3h8', 'SCALAR')] + [('c4h10', 'SCALAR')] + [('ch4', 'SCALAR')] + [('h2', 'SCALAR')]
}
Then "automagically" WeeWX-MQTTSubscribe imports the Loop records it receives (an example :: {"dateTime":1593633630,"h2":0.08} )
And the H2 column (in this example) gets data... archiving works, etc.
Thanks for the pointers... I wouldn't have thought that was all that I needed to do... but that's it... very easy.
Earl