How to migrate a system from SAP HEC to another cloud?

Hi.
If we want to migrate BS on HANA and SAP Enterprise Portal systems from HEC to another cloud, what will be our steps?
How HANA db backups will be made available to us?
Can we boot hosts from a custom CD to backup whole file system of an SAP AS host or host with TREX installed? If not, how SAP will delever such a backup for us?
If these requests are fully custom and should be requested via support, how quick they are fullfilled?