If I understand correctly, you want to pass parameters to the constructor of your service implementation class. You can to this by passing an instance of the service class to the ServiceHost
constructor, instead of its type. That is:
// Create the service instance
var instance = new SmeediServiceHost("some parameters");
// Define the service host using the above instance
this._smeediPluginServiceHost = new ServiceHost(instance, smeediServiceUri);
Caution - using this approach means you are using a singleton instance of the service class. If you need a new instance per session or per request, then consider using a ServiceHostFactory
as described in this answer.