Well, whaddya know -- IT WORKED!
(I've seen it documented as -T3226, but BOL says use /T3226 so I switched to that syntax.)
So it appears that using DBCC to set a trace flag has only a "local" scope, whereas setting it in the startup parameters has a "global" scope. I have not seen this difference mentioned anywhere.
It is SOOOO nice to see a CLEAN and navigable event log at last!
Thanks again to all that helped!