The part number is not on the ECM. I took my ECM out when the hestitation TSB was issued and there is nothing on it except for a serial number. You have to use a Consult II to pull down the part number. The dealer showed me how this is done when I brought the car in for the TSB.
The ECU is located on the floor directly behind the radio. You do NOT need to remove any glove box, dash, or vents to access it. There is a black plastic cover with 2 round plastic snaps that cover the ECU. From the driver's side, the cover is directly beside the gas pedal. Pull on the cover to remove it, and there is the ECU. The ECU has (4) 8mm screws that hold it to the mounting bracket. Then it slides out towards the passenger's side.
As for the part number, you need the Consult-II to get it. But you also need a code that is written on top of the ECU if you are looking for a junkyard spare. You can see this code from the passenger's side without removing the ECU from the mounting bracket (You will need a flashlight). The number should be A56-***-** or something like that.