Im not fully following how you are wanting to set this up.
If you are wanting to have a wireless set up instead of running an ethernet cable through the house, you can buy a wireless router, connect the modem to the wireless router via ethernet and then connect wireless to the router.
It would go like this;
Cable Modem --> [ethernet cable] --> Wireless Router --> [wireless signal] --> Laptop/PC with wireless card
If this doesn't help or is different to how you want to set up post back and i'll try again
~ E-Mu ~
"Emu, You Moo, We All Moo for Emu!" <-- Thanks to Animal
"If at first you don't succeed; call it version 1.0"