Note: I have learned that this method may not work in Racepak's G2X units. It has been working well with my Traqmate for the past year.
So after a couple months of putting this off, I finally decided to tackle being able to log RPM data with my Traqmate Complete. I pulled out my Bentley and looked for a suitable tap. I really didn't want to pull apart my cluster and knew there had to be a place that was easily accessible. Hopefully this helps others out there have delayed setting this up in fear of screwing anything up. There are several other methods that could work, but this worked for me on my 2004 E46 M3 and was a painless install. These instructions should work on any year E46 M3, but follow these at your own risk. I am not responsible for any damage you make to either your vehicle or Traqmate unit.
(1) Start by disconnecting the negative terminal on your battery.
(2) Open the hood and locate the ECU cover against the firewall on the driver's side of the car. Remove the four torx screws.
(3) Locate the ignition coil harness. The harness is located on the left hand side of the panel. There will be the following colors in the harness -- black/white, black/red, black/green, black/violet, black/yellow, and black/blue, and brown.
(4) Locate the black/violet wire in the harness (lower right in harness). This is the one we're interested in.
(5) Tap into the black/violet wire. I used a wire tap from Radio Shack. Use whatever you're comfortable using. Be sure to leave yourself some room between the tap and the harness in case you ever need to remove it for whatever reason.
(6) Head back into the cabin. Remove this panel below the steering column. It's held in at four locations. You need to unplug the OBD plug and a few other connectors in order to pull it out of the car.
(7) You can access this hole via the ECU compartment. There's a grommet as well to the upper right that would also work.
(8) Route the wire back to the Traqmate sensor unit and to the TraqSync cable.
(9) Open the TraqSync connector. Flip the dip switch from (E) for Electronic to (C) for Coil. Connect the wire to the TraqSync cable.
(10) Head to your computer. Connect the Traqmate Display Unit to the PC. Open up TraqView/TraqStudio and connect to the unit. Open the Traqmate User Data configuration screen.
(11) Select the car and enter the weight, rev warning, and rev limit. Enter '1' for number of cylinders. This is the correct RPM multiplier that I found to work accurately with the E46 M3. YMMV. Save the changes to the Display Unit.
(12) Head back to the car and reconnect the negative terminal to the battery. Plug the Display Unit in and turn the car and Traqmate on. Go into "Record | Tach and Speed" on the Display Unit. Check out your new RPM data on the Traqmate!
(13) Have a beer.