Select the musical scale you'd like to use. A traditional Arabic scale includes quarter notes, but these are not available on Euro-American-style keyboards. However, Scott Storch's Arabic sounds can be attained by playing the locrian major scale, the double harmonic major scale or the double harmonic minor scale.
Try out the different scales on a keyboard to see which you like best. The notes in the locrian major scale are C, D, E, F, G flat, A flat and B flat. The notes in the double harmonic major scale are C, D flat, E, F, G, A flat and B. Finally, the notes in the double harmonic minor scale are C, D, E flat, F sharp, G, A flat and B.
Learn to play your favorite of the three scales automatically.
Set your keyboard effect to an instrument used in Arabic music, as Scott Storch would. Clarinet, strings or oud are good choices, if you have them available on your keyboard.
Play around on your keyboard to get just the right combination of notes. Remember that you don't have to play the scale in order. Skipping around on the scale gives you innumerable Arabic-sounding combinations.
Loop one of the note sequences that you figured out, either by playing it over and over the same way, or by recording it and looping it in a music-production program. Since Scott Storch produces for hip-hop and rap, his songs contain hooks and sequences that are looped throughout.