You can use the operatorCompanyId header in the REST API to impersonate a user as tenant operator. When a REST API call is issued, the role associated with the tenant operator for the company takes effect and enables the tenant operator to perform the operation.
Example
This REST API creates a disk library as a tenant operator for the company with ID 10.
POST webservice/Library HTTP/1.1
Host: client.mydomain.com
Accept: application/xml
Authtoken: QSDK 38568012f4d1e8ee1841d283a47aa3ba78e124ea58354b5fc60f4dab8a63347d05cf5552484dafda3bfa4c5db84e580b1cb37bcf8e65b39f7f8549a443e6f78a2c7be3f31b3d845e24776c835e498e8e883bb40c46bd15af4f40ca94e823acedcdd4e9659e74b34a07a85c4586cd2ed914b6dce015874783ef768fda78183a4208930954a377f66eb56c8b92cexampl4s437a19317ca6ce7f3233d5a01aca35dbad93468b833f2cf71010809006a937670adce711ca8be46638e8
Content-type: application/xml
operatorCompanyId: 10
<EVGui_ConfigureStorageLibraryReq isConfigRequired="1">
<library mediaAgentId="1234" libraryName="library001" mountPath="c:\library001" loginName="" password="" opType="1"/>
</EVGui_ConfigureStorageLibraryReq>