If you wanna do the trick with the trem bar , use the 12th harmonics on all strings (2 strings only at a time) .
1)Dive the bar
2)Pick the harmonics , say 12th at D & G strings
3)Raise the bar
repeat with other strings.

Or you might wanna try the slide in case you have one , it's easier to explain :
1)Place your slide on the D & G strings , pick , then move a couple of frets higher ... Then slide down fast and repeat to simulate gear changing.
Kirk Hammett did that in S&M version of "Fuel".