When you kill him, grab his uniform. Now you go up to the valet station at the hotel, looking all snazzy in yoru red and whites. Stand with the other two. "Ah, you must be the new boy ... get in line!" The DA is driving a blue merit. It's a squarish sedan car. First a lady comes a convertible. Be patient, it's going to take a while. The second car in will come over - the other guy says "that's the DA". So they're quite helpful :)

Note that you can't kill the other valets to help your chances :)

Get the car and drive it over to your garage, as marked by the yellow spot. Drugs are going to be planted on the car. Drive up to your garage door and instantly you're ready to roll again. If you damage the car, you have to go back to your garage to get the car repaired. You have a timer to do this - the DA isn't going to stay at the hotel for a month.

Get the car back to the garage and then race to the phone to call it in. The cops some screaming in, "He's got half of Mexico in here ..." Off they go.

Mission passed!

Now you can do Valet missions and you have a valet uniform in your wardrobe.

You also get a call from Cesar about the drugs.

Grand Theft Auto San Andreas Walkthrough