You can use the _cn header in the REST API to view details of a remote CommCell that is registered as a service CommCell.
Example
This example retrieves all the clients in the remote CommCell.
GET webservice/client
Accept: application/xml
Authtoken: QSDK 38568012f4d1e8ee1841d283a47aa3ba78e124ea58354b5fc60f4dab8a63347d05cf5552484dafda3bfa4c5db84e580b1cb37bcf8e65b39f7f8549a443e6f78a2c7be3f31b3d845e24776c835e498e8e883bb40c46bd15af4f40ca94e823acedcdd4e9659e74b34a07a85c4586cd2ed914b6dce015874783ef768fda78183a4208930954a377f66eb56c8b92cexampl4s437a19317ca6ce7f3233d5a01aca35dbad93468b833f2cf71010809006a937670adce711ca8be46638e8
_cn: remoteCommcellName