Ask Slashdot:Fun with IPs

Iris writes " I have a problem that i am sure slashdot readers could help with. I have a friend that has a class C block of IP's that is not in use. I know it is possible to create a IPsec, NAT, or L2TP tunnel between out machines so i can use his IP's on my network, but i can not find any good information on this. Can anyone help our suggest a place to look for information. And yes i have looked into PPTP but decided against it."