maybe this whitepaper is of help
Oracle VM Server for SPARC Best Practices
there is a chapter "Best Practices for Live Migration"
So in my opinion you need shared disks: "Guest domains must use networked storage, and each virtual disk backend in the domain to be migrated must be defined on the target machine. This shared storage can be a SAN disk"
Standart migrate utility require shared disk.
So you can not migrate LDOM. But you can configure new LDOM on other host and copy all disks of original LDOM.
It's difficult to give proper suggestions without knowledge of details.
A procedure might vastly differ, e.g. if the ldom disk is a zvol rather than a directly attached disk and you might be even better of if you run zfs within the 'guest' domain, but not necessarily so.
Do you have constraints on allowed downtime, physical access to the servers, some nfs server that might temporarily provide a properly sized 'shared' disk, some high bandwidth low latency connection between the servers? Is there some firewall regime that strictly forbids primary to primary connections or are you free to chose the appropriate tooling and adjust the environment? Do you have to migrate a singe disk domain or has it a wealth of disks containing terrabytes of a busy database ,...
Do you have additional disks to provide at least the same capacity on the source side?
You can easily see, there are quite a few degrees of freedom.