You can't directly access properties of a service. If you need to
support communication with a service, then you need to implement some
sort of interprocess communication. Since your using .NET - remoting
or WCF would be a good choice.
If all you need is to send commands (no responses), it is possible to
use the ServiceController class to send custom integer commands to a
service. In your service class, you would override servicebases
OnCustomCommand method.