Watch the What About Locrian? online guitar lesson by David Wallimann from Guitar DNA: CAGED Soloing
By now you should know the E position for 3 Major modes and 3 minor modes. By memorizing the E position of the Locrian mode you'll be able to play all the modes all over the fretboard. All you need to do is memorize the following order: Ionian, Dorian, Phrygian, Lydian, Mixolydian, Aeolian, and Locrian.