Well I don't think Keysight will be willing to help with this so I am going to have to walk through the code and see if the information I need is there. I suspect it is based on what I've found so far
1) RegisterNativeSecureStorageCallbacks
2) SecureStorage_Add
3) SecureStorage_Clear
4) SecureStorage_Free
5) SecureStorage_ModelNumber
6) SecureStorage_Read
7) SecureStorage_ReadCommonArea
SecureStorage_Retrieve
9) SecureStorage_SerialNumber
10) SecureStorage_Write
It appears that there is the ability to write to the secure storage in these DLL's. Will take some time to figure out. I'll post back when I do. Whether or not it can be done with SCPI command is still a mystery as those DLL's appear to be obsfucated so that will be a piece of work since this is not at all my specialty.