I downloaded Brl-Cad, but it is not a very friendly program. There is some (obtuse) pdf documentation.
It seems to consist of 3 programs.
MGED is the geometry editor.
RtWizard is for ray trace.
Archer is for ?

One of the several pdf manuals gives command line instructions to convert from a Euclid database: euclid-g i (Euclid_db filename) o (brlcad_db filename).
The option "i" is for input file. The option "o" is for output file

Finally found the program euclid-g.exe, in the BrlCad .bin folder. It produces a command line box for typing in instructions.
Not sure where the input and output files go, maybe in the .bin folder? ...

- Brian