As I am sure you are aware all version 5.5.x.x of TSM are out of support.
However, using verion 5.5 of the Operational Reporting with any version 5.5.x.x TSM server did not require a custom xml file, that was only required when using the 5.5 Op Reporting with a version 6 or 7 TSM server as outlined here: https://www-304.ibm.com/support/docview.wss?uid=swg27019794
Once installed and configured to use it for a any version 5.5 TSM server you should only have to open the Operational Reporting Management Console, right click on Tivoli Storage Manager and select "Add a TSM Server".
In the TSM Computer Resource Properties window enter the server name, select an operating system, check "Include Report Features".
Next check the "TSM Web Administrator box, this enables the management console to communicate with the TSM server.
Enter A name into the Server field, the TSM server's fully qualified domain name or IP in the TCP/IP address box, port number 1500 in the TCP field, and 1580 in the HTTP box, then select the add button, and then select "Apply".
The TSM server should appear in the left pane of the Operational Reporting console, expand it and navigate to the reporting section where you can enable or add custom reports.
The Server Admin Guide explains this in detail and also adds information on compleing these tasks from the command line as well.
-Rick Adamson