An automatic ECU can be used just fine for converting a manual car, however reverse lock-out (the thing that stops you shifting all the way to the right and selecting reverse when rolling forward) won't function properly. The ECU performs as a manual ECU otherwise.
An ECU from the '07-08 Facelift 1st Generation Acura TSX is needed to convert all European and Japanese CL9/CM2 for use with Hondata's FlashPro engine management solution. While pricey, this is the best and most tried and tested solution for 7th Gen Accord owners. Used ECUs are extremely hard to come by as all Pre-Facelift TSX owners in the states also require them for FlashPro use as well. Coupled with trying to convince people to post them for abroad, many choose to go for a brand new ECU.
Acura have raised pricing on these ECUs recently, and unfortunately with the exchange rate and import as well that makes them a pricey acquisition. However, as CL9 owners know, engine management is key when tasked with transforming the slow stock K24A3 into the Type-R beating monster the car is capable of becoming.
There's a monster guide covering everything about the conversion here written by H-Tune staff member, Leo. Any questions about the process, feel free to drop us a message.