Hi,
Possible but needs a lot of planning according to your enviroment.
1. Create a table defining the ip addresses for cluster and members for every interface
2. Prepare script with routes, interfaces, etc for the new gateway
3. Install the new gateway, configure with previous script
4. Take captures for Network topology, IA configuration, vpn domain, remote access, etc in the old gateway object at smartconsole
5. Reset SIC in old gateway, NOT INITIALIZE
6. Remove the old gateway object from all VPN communities (do not delete the communities)
7. Disable VPN blade in old gateway object, publish
8. Change the name and ipv4 of the old gateway object, publish
9. Enable vpn blade again in old gateway, publish, delete VPN certificate, accept warnings, a new cert will be created. Publish
10. Create cluster object in smartconsole, use the IP address you want to Keep as VIP, go to cluster members and write the hostname of the new gateway, put IP and SIC password
11. In the cluster object Get interfaces without topology, at this moment the cluster has only one member, the new gateway.
12. Copy all the configuration from the captures from step 4 (IA, remote access, IA, etc)
13. Check all the places where old gateway was used and replace with the cluster (rigth click, where used)
14. Add the cluster object to VPN communities
15. Push policy (services outage)
16. Unplug old gateway, plug new gateway
17. Change hostname in old gateway trough CLI, reset SIC
18. Change interfaces IPs in old gateway according to your table in step one
19. Plug cables again to old gateway
20. Put the new SIC password in smartconsole for old gateway
21. Add old gateway to cluster
21. Get interfaces in cluster without topology
22. Push policy
23. Install licences contracts, check services.