copy the cleo scripts into your cleo directory

copy the maps files and then go to maps -> LA -> replace the files: "LAhills" and "LAhills.IPL

Then you're ready to start the game. 

If the cleo files doesn't make the vehicles spawn imeddiately, 
you have to start new game. It is possible when you have done this, that there is still missing a
vehicle, then you just have to go far away, and then come back(for example go to the airport and then go back), then it should work 100%  