I would NOT advise that course of action. Unless you're REALLY into electronics and know all about soldering and components I would either:
1. Have the unit serviced by Sony, but if that's not possible
2. Get a PCMCIA Network Adaptor and call it a day
If you're dead set on doing this you can always talk to
this place and see what they have. They also have a repair option if you fark it up...
Good luck!