CIsco 2800 Router NAT/PAT based on destination address

Hello,

Can anyone give me an example config on how to PAT based on destination address?

Site A:
Cisco C2800 ISR
LAN: 10.10.10.0/24
Public address: 1.1.1.1
VPN Peer 2.2.2.2

Site B:
Cisco Concentrator 3005
LAN: 172.22.22.0/24
Public address: 2.2.2.2
VPN Peer 1.1.1.1


At site (A) I have a Cisco 2800 router with a VPN connection to site B.
On sites A's router, I need to configure PAT only when destined for host 172.22.22.22 that is on the other side of the VPN tunnel. All traffic from network 10.10.10.0/24 will be PATed to 172.21.21.21.
All other traffic PAT's the same out their respective interface.


Any help would be much appreciated.

Thanks!