The script only works if Carl is in SF. The mod also adds a car park where there are buses. Just come to the car park or find any bus (COACH or BUS), sit down and press "submission". And then the mission will begin. Stops will be marked on the map.
For each stop you will be given +100$! There is a surprise waiting for you at the end!
In the second version the script is better, the markers on the map are now the normal size, and people getting off the bus will disperse in different directions. Parked buses will no longer spawn if the script is removed.