you can use the environement variable "MGC_RVEDB_DIR". After that you can point it to a directory with your shared file .rvedb.
Example to set your .rvedb as standard:
calibre -rve -drc out.rdb
[you modify the GUI as you like and close it]
[shared ".rvedb" in the directory /usr/share/.(you have to be root)]
cp ~/.rvedb /usr/share/
[setup that for all the users of your system in /etc/profile. Add the following file]
[or easily direct in your session]
setenv MGC_RVEDB_DIR /usr/share/
Have a nice day!