The Hondata website has all the info you need:
Quote from Hondata:
How does this work for the 04-06 TSX?
FlashPro does not work with the 04-06 ECU, so an 07 or 08 ECU is required. The Honda part numbers are 37820-RBB-A21 for manual and 37820-RBB-A71 for the automatic. They sell for a little over $600. The 07/08 ECU plugs in and mounts where the original ECU is located. Hondata provides a wiring adapter for $50 which links the ECU programming pins to the DLC. The ECU is installed, a Honda dealer will need to match the immobilizer to the new ECU.