Audi A4 B5
Hi found this when i needed to get a cable for fog lights through the firewall to the engine compartment without drilling holes or breaking gromets.

1.Take dash side panel off just pull it out (just like the drivers side to get to fuse box)

2 Underneath you will see two 8mm screws holding the glove compartment up take them off open glove compartment and at the top at the lock there is another 8mm screw and then look inside to the right you will see another two 8mmm screws with them off the glove compartment comes straight out and just disconnect the electrical conections and pull the whole lot out.

3 Behind that is the steering colum large grommet for left hand drive but its hard to get too! so just to the left you will see a small round gromet with one cable comming through with a connector on to it, push the gromet through towards the engine.

4. Then look above the front wheel and you will see the gromet and its actually for the abs sensor to the front brakes. I took the front passengers wheel off for easier access.

5. I just pushed my cable down the same route as this cable (used some soapy water) through the grommet and thats it! push the gromet back in,i then just pulled the cable through a hole into the engine compartment next to the steering rack and you are safely through the firewall without getting any leaks into the cabin dead easy.replace glove box, tools required one 8mm socket.