Glad to hear you got an ST, it's unfortunate it came equipped with the AUTO. I don't think you're going to have much luck locating the factory EK10 manual box but I ran my ST using the K10 tranny from a Canadian Micra. The only risk that I can see is the March/Micra tranny was not designed for the output of the ST engine so it could grenade on you.
You will need the following for the conversion.
Rear Transmission mounts
Side Transmission mount
Pedal box from a Manual
Reverse switch plug
The installation is pretty straight forward. The intercooler will lose all of the mounting points so it will be just floating around. If you come up with any other questions PM/DM me. I put an ST engine in my Figaro but I did the manual conversion before the engine swap.