We can change the M600 to W950, so the other way should work.

The key is to mix the firmwares (essentially M600 OS with W950 hardware drivers).

M600i has:
M2 memorystick support
QWERTY keypad

W950i has:
4GB of internal memory
flushed keypad (+dedicated music buttons)
Flash Lite support
RDS radio
the walkman mediaplayer application

*and of course the different appearance