If you want to update the Scan At Start Up for all the machine through the registry, then you need to use the Agent Configuration found under Admin->Agent Settings->Help Card, there you will have the config file and the parameters that is needed to update the registry settings and deploy the same using GPO.
Also you can go to our Demo site using http://itildemo.servicedeskplus.com, there you need to go to Admin->Windows Agent Settings->"How to change the configurations in all agents after they are deployed?", here you will find the same instructions.
Regards,
Santhosh Mahiban
SDP Support - FAQ
ServiceDesk Plus - Help Desk Software of your Choice
Also you can go to our Demo site using http://itildemo.servicedeskplus.com, there you need to go to Admin->Windows Agent Settings->"How to change the configurations in all agents after they are deployed?", here you will find the same instructions.
Regards,
Santhosh Mahiban
SDP Support - FAQ
ServiceDesk Plus - Help Desk Software of your Choice