The short answer to this is no. An administrator will still have to change the service accounts password, Please see here:
In searching the IM documentation for endpoint password management. I do not see anywhere in our documentation where an application, like Siteminder, can initiate a password change.
Siteminder itself does not have the ability to call out to other application APIs so cannot initiate a TEWS call to IM to reset the user's password in IM to synch to an endpoint.
There is no "sweeping" process in IM where you could call a password change to an endpoint.
Password changes could be initiated by an external TEWS client, and you could use policy express to generate a password, but doing this could be dangerous.