Painters of full size cars call it Metalflake but scaled down, and the particles are scaled down, it's called Fasglitter.
To spray Fasglitter mix it with Faskoat (part no 40200), around one part glitter to four parts Faskoat by volume is a good starting point as this will not put too much glitter on each coat and allow how it is covering to be gauged. Once experience is gained the proportions can be altered. The pressure of the airbrush needs to be set high, around 70 psi, and holding it back a little from the bodyshell, around 40 to 50 cm, with the needle set open just lay coats on drying each one before applying the next. How much to put on is really down to personal taste but to begin with three or four coats of glitter is a good starting point. The layers of glitter are then backed with a complimentary colour to finish the job.
To be safe and to satisfy personal taste it's always wise the first time you use a paint to have a try-out on a piece of lexan offcut to get used to application and in the case of Fasglitter get the number of layers and backing colour right.