Shorewall users - Oct 2003 - configuration for VPN

Hello!
I have a problem that bothers me whole day: I have one
firewall/router connected directly to ISP. Another firewall/router is
connected to the first one. A PC with VPN client is connected to the
second router.
I am using reserved IP addresses on both firewalls.

My questions are:
1. How do I have to edit shorewall configuration files?
2. Do I need VPN/IPsec support in kernel?

Thanks in adv.

Jernej