Seconded. Currently, it exists in the MSI, but it should really be a seperate proprery for each one, not one big property for everything. Currently, in the MSI property called  "SERVICE_CLIENT_LAUNCH_PARAMETERS" you will see c=&c=&c=&c=&c=&c=&c=&c=&

In between each = and & you can define the custom property in a switch. But, again, it would be MUCH easier if you could edit each on individually.