Volvo Repair: TCM, transmission control, firmware

Question
Where is the TCM or Transmission Control Module located? Could I replace it myself. They want 450. for the TCM. I want to save some on the labor!!!
They said I needed one after they updated the ECM software. Which I never asked them to update the software to begin with! Any help on this one?

Answer
  Jeff, it sounds like the TCM was bad all along? If it wouldn't take the update, that must be the case. As far as location, I think they are on the left front top of the saddle? I can't remember them all? Try a component locater to be sure. Easy to change. Have to get all the latest firmware loaded onto it though.

Mark