The name which includes the spirits of Mercury is Merhuyez, that of its spirit in the height is Amirez, that in the depth Hytyz, that to the right hand side Cehuz , that to the left Deriz, that of the front Maylez, Dehedyz behind: that of his movement in the heavens and its progression in the signs is Mehendiz. The name which includes all these preceding (it is so to speak the radix and the type of all those preceding) is Merhuyez, named above.
Picatrix, Book III, Chapter 9
Translation & Ritual Usage Ideas by Nigel Jackson
Used Courtesy of Renaissaince Astrology Website
In practice these may be used viewing a ray of orange energy coming into your heart center from the appropriate direction as each name is invoked. Then walk a circle of the ritual space, tracing a circle of orange light as you go invoking the name Mehendiz. Return to the center and visualizing all of the rays while invoking Merhuyez.