This sounds like a feasible swap, but I'm no authority on how to pull it off. You might find this link (from Rotary Resurrection) useful to reseach what is involved:
http://www.rotaryresurrection.com/2n...to_5speed.html
This lays out the work involved in the more common AT to manual 5 speed swap on US spec FC's. Reading this with a reverse-engineering perspective may answer some of your questions, or at least point you in the right direction.