Hello Kalai.
You are on the right track using the unmanaged detector to find clients that are unmanaged. Once that is finished, you have a few options. Please look over these articles:
About client deployment methods
http://www.symantec.com/docs/HOWTO80807
Deploying clients by using Remote Push
http://www.symantec.com/docs/HOWTO80788
Let me know if I can be of further help.
Brian