If you are using IE then this is not directly possible. Pega Robotics needs to start any of the applications it is going to operate with (or in the case of MonitorAll, be running before the application is started). If you are using the Universal Web Adapter for Chrome or Firefox, then the plugin will be launched with the browser allowing it to be hooked when Runtime starts.
For IE, you could potentially use MonitorAll as the StartMethod for your adapter, however this will then hook every instance of IE launched by the user. This is not suggested though.