You didn't mention the devices b/w whom you want to configure site-to-site VPN.
I hope u are using PIX/ASA.
hope this helps:-
http://www.cisco.com/en/US/docs/security/asa/asa80/configuration/guide/site2sit.html
http://www.cisco.com/en/US/products/ps6120/products_configuration_example09186a00805e8c80.shtml
and on ASA 8.x there is a hidden command which can show you what steps to follow to complete the setup
ASA-5510-8x(config)# vpnsetup ?
Configure mode commands/options:
IPSec-remote-access Display IPSec Remote Access Configuration Commands
L2tp-remote-access Display L2TP/IPSec Configuration Commands
Site-to-site Display IPSec Site-to-Site Configuration Commands
Ssl-remote-access Display SSL Remote Access Configuration Commands
