formatting seconds in time

Hi,

Can you help me with my MDX. I have a datawarehouse which have a table agent_time. Inside it are fields like the agent_id and agent_logintime. The agent_logintime specifies the duration of time in seconds the agent is logged into the system and are in bigInt. Therefore, if the agent is logged in for 3 hrs, the agent_logintime is 10,800. In Analysis Services, how do I do it in MDX if I want to add all the logintime of the agents and display them, instead of in seconds, i want them in time format. Say, 98:45:23 login time (98 hours, 45 minutes and 23 seconds).

I badly need your help!

Thanks a lot.

Cherrie