2003 audi tt tach wire

I have been through everything with this remote start/ alarm install. Audis really do make nothing easy. I searched for CAN wires for 2 days to no avail. Finally, I decided to wire the alarm in directly. When it was almost completed I got to the tach wire portion of the install and noticed that the location was at the ECU. Well, the ECU is not easy to get at in any way with the 2003 Audi TT. Questions: Is there any other way to get the tach signal (fuel injectors, ignition coil) and if so what are the wire colors? Can I simply tap into the grounded main wire for the coils? If not, how do I remove the sheild over the ecu harness? Thanks.

Here is the information from DEI:

The ECM is under the plastic cover on the firewall, under the hood.

Audiovox Tech site recommends just using an injector wire.  You would use the wire that is not a common color to all injectors...i.e., Not RED / purple.