Watch the Single-Line Substitutions online guitar lesson by John Stowell from Modern Jazz Progressions
It's important to reference the basic chord tones in your lines as you layer the extensions of the melodic and harmonic minor modes over the dominant chord.
Once you're able to visualize and connect these sounds on the neck, the next step is to apply these extended sounds in the context of a common turnaround such as a II-V-I progression.
Melodic and harmonic minor chords also function well as altered dominant chords, as I demonstrate here.
Play everything slowly in the beginning to be able to connect patterns on the neck and acclimate your ear.