Working with Objects - Adobe Illustrator CS6 on Demand - page 168

Create a Perspective Grid Preset
Click the View menu, point to Perspective Grid , and then click Define Grid to
create a grid (steps 3 thru 6) or manually create one.
Click the View menu, point to Perspective Grid , and then click Save Grid As
Preset .
Type a name for the preset.
Specify the perspective grid settings you want.
Specify the grid color & opacity settings you want.
Click OK .