1. Buy a wireless router/modem, connect it directly to the phone point, and install a wireless network card in one of your computer's PCI slots. That's the 'no wires' solution.
2. Buy a modem/router and connect it to your computer via an ethernet cable, in which case you would - as you said - use the computer's LAN port.
My advice is to buy a modem/router combination, and slot a PCI wireless adapter into your computer. An hour or so of setting up, and you have a wireless broadband service.