An HP MSL (1/8 autoloader, 2024, 4048 & 8096) has 3 different accounts which can be used to logon to the RMI (web-based management interface).
The accounts User & Administrator can be manually configured. The Service user account cannot be changed. The password for the Service account is 42311324.
Please note in later firmware versions of the tape library, the RMI requires both the Administrator & Service password to be filled in to access the service pages.
Hope this helps!