Just as the standard major pentatonic scale can be used to create the sounds of major modes, the major pentatonic b6 scale can be used to create the sounds of melodic minor modes.
The major pentatonic b6 scale is, well, a major pentatonic scale with a b6 instead of a major 6th. In C, it is spelled: C D E G Ab. This scale sounds good if played for 2 octaves, because of the jump between Ab and C in the next octave; it gives a nice harmonic minor kind of sound. This scale is great for making melodic minor sounds, because it gets to the core notes of what each melodic minor mode is.
Let’s take the first one, which is simply melodic minor. You play this scale over a minor/major 7 chord. So let’s take Dmin maj7, which is spelled D F A C#. Notice the minor third and major 7th. In jazz, we use the ascending melodic minor scale to match this chord, and don’t change when we descend. We would use D melodic minor in this case, which is spelled: D E F G A B C#. Notice how the scale contains all the notes of the chord.
To use the major pentatonic b6 over this, you would start from A and play: A B C# E F. This scale gets all the essentials of the D melodic minor sound, you get a fifth, major sixth, a major seventh, a ninth, and the minor third. Plus you get a cool jump between F and A. Have fun trying this out, it really freaks people’s ears out. Enjoy!