There are various places.
- if the source can supply the required voltage and current, you could place it between 'high to run' and ground.
The next step is 'after' Q2, but that has a switch in parellel, so your light will light up if that is pressed too. You could extend the circuit with a resistor or a few diodes to prevent this.
- Q2 switches on when 'high to run' is high, so you could place the light between Q2's collector and V_battery.
Next is between the collector of Q1 and ground. Like the collector of Q1, it is also activated when the switch is pressed (and prevent this parallel activation is a bit more involved), so maybe that is not what you want.
One additional note: if you use a LED on any of those places, don't forget the series resistor.