i looked into this dude, to do a proper conversion you need a lsd box which will set you back a fair bit, in the end i worked out it'd be cheaper to buy a manual car and sell the auto.... i bought a manual, just not a naturally aspirated one
but all the same, if you love your car that much, go ahead, i think i roughly worked it out to be around $2,500 for a parts, ie. proper clutch & box, slave, pedal and a few other bits and pieces.