"remote" start/stop of relay/snoop output

I asked that question some years ago, and IIRC then it was not possible, 
so I resorted to add an external filter app in order to start/stop 
relays on an already running app.
Filter app solved partially the problem : I could get the relay part I 
needed, but the speed was about the same as dumping the full relay on file.
Now (as it was years ago for autocad r14...) I'm trying to trace some 
calls in autocad2005, but relay log becomes easily 10-20 GB in size, so 
quite useless.

I think the log start/stop feature could be a *very* useful way to 
isolate needed relay part and to speed up tests.
Is it still not possible nor faisible ?

Max