I did mine (drivers side) in about 30-45 minutes. Go from the headlight -- that's the easiest. Remove the headlight (mine is European version), unplug from the harness. Assuming you have a European headlight, the wires are easily removed from the two plugs. The six-pin plug separates by just removing the screw. Just lift the wires out. Make sure you know which wire goes into which space (I drew a diagram)). As I recall (almost a year now) the other plug (or receptacle) is a three-pin version where the wires are attached to copper/metal tabs that are held in the connector via spring action. I used a small slotted screwdriver and needle-nose pliers to remove those -- not hard to do.
Push the rubber grommet and wires into the wheelwell. slide off the old grommet. Clean the wires then lubricate them with somehting a silicone based product like armour all -- makes sliding the new grommet on that much easier. then I taped the wires together to make the longest, thinnest wire bundle I could -- then slide on the new grommet.
Feed the whole bundle back into the headlight bucket until the grommet is just now pulled flush with the headlight bucket. I then used nylon interior trim tools to coax the grommet flange into the headlight bucket -- again with lots of armour all sprayed on it. Remove any tape you used to bundle the wires, then put the wires back into the plugs, attach the headlight, fasten to the bucket, snap the trim ring back on and you are done. Might be a good time to replace the seal between the headlight frame and the bucket/fender.
