Dialup sharing in simple LAN

[O. Sinclair]

In one project I work with I plan to install some small LANs (3-4 PCs) 
on a simple wired network and then have them share a dial-up internet 
connection (reason being they are far away from any broadband and 
satellite costs an arm and a leg).

anyone knows a software or method of achieving this as "support-free" as 
possible? meaning that if one PC calls for internet access the connected 
PC should call and then hang up when all is finished without human 
intervention.

Sinclair