Watch the Extreme Customization! online guitar lesson by Rob Garland from The Guitarist's Pentathlon
Against the Bb7ALT chord I'm playing Bbm pentatonic with added notes such as D (3rd), E (b5th), G (6th), A Nat. 7th), C (9th) and also playing outside for more tension. There are more to explore such as b9 and #5. These ideas can be used on regular or altered dominant chords, depending on the type of sound you want to create. Chromatic lines can be used in jazz, country, progressive rock, fusion and well, everywhere!