I'm not famliliar with the song you mentioned, but when I think of west coast whistle..I think of the likes of Ohio Players and producers such as Dr. Dre..So I am going off of that..To get a close sound as the Ohio Players use, in the video NavieD posted.........
3xOsc...if you learn how that works, you can produce the sound yourself.. I'm pretty sure the whistle sound in question is a type of Saw wave... So set up a 3xOsc, and put em on Saw....I set OSC 1&2 to +12 on the CRS knob..and left the 3rd one in the middle...Then goto the INS tab, and once there, click the VOL tab...Turn your attack all the way down, turn your release all the way down...turn your sustain all the way up. You can leave Decay and Hold how it is...Then goto the MISC tab, and in the Polyphony section, click Porta and Mono...and turn the Slide knob slighty past the halfway point..Still in the settings window, you see the small keyboard..By default you see that above "C5" is an orange high light...What I did was move that to C7..by simply RIGHT! Clicking "C7"..
Now I played the piace from Dr. Dre's "Nuthin But A G Thang", in the 6th Octave in the piano roll..and with the settings explained above, if implemented correctly, you should get a pretty close sound..Of course you will also NEED to do some Effects processing, such as some EQ at the least...
And keep in mind, when you click Porta and Mono...you must slightly extend your notes in the piano roll for the effect to work...