Here is the user manual of CANEMU CAN filter 3-in-1 emulator for BMW, Mercedes-Benz and Renault, the instruction here especially for BMW users (with BMW CAS4 & F20, F30 with FEM).
– CANEMU can filter wiring for BMW CAS4:
Remove CAS4 from car, no need to disconnect battery, just let car for 1 minute, car go to sleep mode and now you can disconnect CAS4.
– prepare CANEMU board: solder 1 and 3 configuration points. use fine KYNAR wire for installation.
– Open CAS4, install CANEMU board like the picture.