Watch the Double Stops online guitar lesson by Brad Carlton from Guitar Lab: Big Blues & Beyond
This lesson restricts you to the 4th and 5th strings when playing double-stops out of E minor pentatonic. As you move up and down the neck, make sure you can see each position scale form that you are in. This will enable you to move along both the string axis and the fret axis thus giving you total mastery of the minor pentatonic scale.
I will demonstrate this approach while improvising over a jam track, then it's your turn to do the same.