Does anyone have any tips on how to do this so that I don't mess up the texture of the buttercream?

Do you have an airbrush? I've never tried it before but I'm wondering if you could add vodka to the luster dust and airbrush it on??? I've only used luster dust on fondant before. I'm curious now so keep us posted on what works for you

sounds gross, but I've seen folks dip a fluffly brush into the luster and then "blow" it off the brush onto the cake. Make sense? there must be something better to "blow" with out there...?

Thanks for the ideas, yes I have an airbrush and I also have a fluffy brush and I think instead of "blowing" the dust I could use the cold air setting on my blowdryer! I knew there would be some ideas out there!