Finally opened a WRC and got an answer: update to 2021.1 as categories have much improved.  :)

Answering myself:

For a system with 8 cores, we will be allowed to use maximum 16 workers. So, to be able to do it and let other processes work with the default queue, we we just need to set the global:

 s ^%SYS("WQM","MaxActiveWorkers","User.Testing")=16

so, when creating the queue it can be done attaching the workers to this queue:

  set queue=$SYSTEM.WorkMgr.%New("/multicompile=1",16,"User.Testing")

I answer myself, in case someone is in the same issue.

WRC response was:
The short answer is that unfortunately there is no stand-alone kit for Atelier, as it is distributed only as a plug-in for Eclipse, and as such it follows the official Eclipse distribution mechanism.

But they gave me a few hints. Finally, I downloaded all the atelier package using wget from another computer, zipped it, copied to the computer and have it installed as local zip package. Worked like a charm :-)

My mistake... the odbc driver name was wrong :'( I can connect now :)

But I see that I have to rewrite the functions because the prepare, execute, fetch, etc attributes doesn't exist in pyODBC :'(

UPDATE: just by changing a few lines allowed me to work with pyODBC.

I can't remove the question, so I answer myself. The problem was at the routine called by the queue: a "lock" instruction seemed to break down everything.

So, removing the line solved the problem :-) Now I just need to know why locking a global messes the whole thing up :-O

I just installed 1.3 and it still not there :O And Intersystems announced they won't be any enhancements from now on.

So I guess this is all we'll get.