Yes.
You can use Fortec's Proxyplus or Winroute Lite on the PC with the modem and then the PC's on the network will be able to talk to the net.
Be warned! it will be slow.
Do you have the network setup? If not then you will need to buy a switch and network cables.
If you have the network then no specific hardware is needed just the software to allow the internet connection to be used by the other PC's.
Gary.