Here are some notes and answers to your question:

In Chapter 8 of the Admin Guide is the following:
Note: You can monitor the users currently connected to an ALM Platform
server. For more information, see Chapter 6, ''Managing User Connections
and Licenses.''

In Chapter 6 on page 162 of the Admin Guide is the following:

? Monitor the users currently connected to an ALM Platform server. For
each user, you can view the domain and project being used, the user's
machine name, the time the user first logged in to the project, and the
time the most recent action was performed. You can also view the client
type connection to the ALM Platform server.

Also, SESSIONS_HISTORY is not a parame![alt text][1]ter but instead is a table of the Site Admin database so if you have access to SQL Server Manager and can connect to the qcsiteadmin_db database,I found this on the HP Quality Center Support & News Forum:

select
PS_ID as 'Session ID',
LS_USER_NAME as 'User Name',
LS_CLIENT_HOST as 'Client System Name',
LS_CLIENT_TYPE as 'Connection Type',
LS_LOGIN_TIME as 'Login Date/Time',
LS_LAST_ACTION_TIME as 'Last Action Date/Time'
FROM td.PROJECT_SESSIONS
JOIN td.LOGIN_SESSIONS on LS_ID=PS_LS_ID
WHERE
PS_DOMAIN_NAME = '' AND
PS_PROJECT_NAME = ''

Here was the link:
http://h30499.www3.hp.com/t5/Quality-Center-Support-and-News/SQL-Query-to-find-who-all-users-are-Idle-for-the-maximum-time/m-p/6328859/highlight/true#M83675

Obviously, you need to put in your ALM Domain Name and ALM Project Name.
When I did that for the ALM_Demo project and Default domain, it looked like this:
select
PS_ID as 'Session ID',
LS_USER_NAME as 'User Name',
LS_CLIENT_HOST as 'Client System Name',
LS_CLIENT_TYPE as 'Connection Type',
LS_LOGIN_TIME as 'Login Date/Time',
LS_LAST_ACTION_TIME as 'Last Action Date/Time'
FROM td.PROJECT_SESSIONS
JOIN td.LOGIN_SESSIONS on LS_ID=PS_LS_ID
WHERE
PS_DOMAIN_NAME = 'Default' AND
PS_PROJECT_NAME = 'ALM_DEMO'

The results are attached to this note.

[1]: /storage/temp/387-cas-26164-r0w1-queryresults.png