how do i put pearl dust on the entire cake frosted in buttercream?

I have not heard of this...but then again I am just a newbie too!! To my understanding you can apply pearl dust to fondant and gumpaste. But, I might be wrong...want to know the answer from more experienced CC's

I just thought of something...maybe if you airbrush it with pearl dust liquid??

It would have to be a spray i think,probably the wilton ones,pearl spray.

I've purchased super pearl spray online. It's a bit expensive but a little goes a long way.
You could probably apply powdered pearl dust to a buttercream cake once it has crusted very well. Using a very soft brush and light hand.

PME pearl dust spray. pricey but worth it. (unless you own an airbrush system, of course).