Guitar World has a post up on the Cherval guitar that Keanu was holding in the photos with Andrew Autin that appeared yesterday. Andrew Autin is a guitarist located in New Orleans. He gave Keanu and Alex Winter a crash course in on-camera shredding.
The Charvel in the photo is a San Dimas Pro Mod. Info on the guitar is at the Charvel website. There are many colors and finishes to chose from but there was not a glitter one which leads me to believe that this one may be custom for the film.