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>*<<*<* to find out your firmware (>= direction of joystick movement)
I got a D750 (aka K750) flashed into W800 myself. It works and it is for free!
You can do it by yourself with the usb cable (DCU-60) that came with the phone.
For CID36 you can use the program Gflash, itīs easy to use.
For CID49 you have to use XS++, you can use that program for CID36 too but itīs just a little more complicated, but just take the time and read about how to handle it!

edit: lol Iīm to slow in typing...