How to enable VPN on Cisco 2900 series router which is configured for dual WAN load balance?

[khasan.netadmin]

I have Cisco 2921 router which is configured as Dual WAN load balancer.
Head Office given me site-to-site Tunnel for both Public IPs ...

I can enable VPN for single ISP (single public IP), Is this will be same for both?

Anyone help please. If possible then include steps to configure and test.

[Philip D'Ath]

Is this a VTI (GRE over IPSec) VPN, or an old style ipsec site to site VPN.  Has the head end got a single IP address or two?

[khasan.netadmin]

One public IP address from head end x.x.x.x/29   and two public IP addresses in my end y.y.y.y/29 and z.z.z.z/29

No, it's not VTI VPN,

Old style IPSec Site-to-Site VPN tunnelling.

We want to connect our LANs