In a nutshell:
1. Lookup the virtual hardware requirements for the platform on which this VM would be running.
2. Download the ISO, JHFA, Deployment Agent and the latest Migration Tools for R80.40 for source version R80.10 or lower (thanks @the_rock for pointing this out) that could be found in sk160736.
3. Create the VM with its network interface terminating on a dead-end network using same name and IP address as 205. Be sure to lazy-zero the storage.
4. Use a multi-homed Windows VM as a jump host for its pre-configuration (one interface connected to your internal network for RDP access, another to a dead-end network for the access to the VM.
5. Mount the R80.40 ISO to that VM and boot from it
6. Configure partitions as necessary.
7. Go through the First Time Configuration Wizard on VM from the Jump Host. Specify the VM to be Management/Primary.
8. From CPUSE, Update Deployment Agent, Install JHFA and (possibly) the Migration Tools (but those may be baked into JHFA)
9. Install migration tools for source versions R80.10 or lower from sk160736 on your 205
10. Perform migrate export procedure on 205 !!!running it from the directory where the new tools are located!!! writing the export file into /var/log/
11. Get the $CPDIR/log/migrate-<YYYY.MM.DD_HH.MM.SS>.log file if export fails. Open TAC SR and upload CPINFO from 205 directly into it.
12. If export is OK, move it to the Jump host and upload using WinSCP to the VM into /var/logs
13. Perform migrate import on VM
14. Again, check HTML report for results this feature is not available for old migration tools
15. If all is well, re-license the VM with the help of your reseller
16. On a go day, disconnect NIC of 205 from the network and move the VMs vNIC from Dead-End network to the same where the 205 was connected to.
17. After about a minute, your gateways will go "green" and you'll start seeing utilization graphs. To be sure, test SIC connectivity from each gateway or a cluster member. You should see "Communicating" in the status.
18. Change Primary Management's object version to R80.40, and the platform to "Open Server" (may happen automatically)
19. Install Database
20. Install policies
21. All done.
--
Fallback:
1. Disconnect vNIC on VM
2. Reconnect NIC on 205
3. Chnage version and platform back to the old one
4. Install Database