To export System Service Manager Management Packs with a PowerShell CMDLET, open the Service Manager Shell with elevated rights and enter the following;
Get-SCSMManagementPack|Export-SCSMManagementPack –Path C:\ExportMP
To export only the Sealed or UnSealed Management Packs you can insert an “where-object” statement. In this example I want to export all Management Packs except the Sealed ones.
Get-SCSMManagementPack|where-object {! $_.Sealed}|Export-SCSMManagementPack –Path C:\ExportUnsealedMP
Additional links; Technet; How to seal a Management Pack; How to unseal a Management Pack