Wouldn't airbrushing it gold work much better? 

I tried that @julia1812 ‍ , airbrushing will not cover up the color on the multi-colored sequins. I didn't realize that you could actually buy white ones to begin with. In any case, I did start by airbrushing but the only way I was able to cover the color was to use gold dust with vodka as shown in the video.-Frank

 How much of the candy sequins will it take to cover a 9" x 4"  round tier? 

@Julia1812, yes, airbrushing WORKS, and is much faster and easier. Also, no need for fondant and nasty piping gel. Final coat your cake with BC as usual and press quins onto sides and top of cake. Chill, then airbrush - WITH A FOOD SAFE DUST.  So easy. 

ALSO....the dust this person uses is INEDIBLE! It's actually ground metal...read the label. Ideale Metal Dusts, available is Silver, Gold and Bronze. Great for display cakes, but should NEVER be used for cakes to be eaten. I'm just a pastry chef tired of seeing rules being bent by cake makers. 

@StellaBaking what safe food dust would you recommend? I can't find anything that would be edible and have good coverage.

Check this out. Decorate SAFELY everyone!

http://artisancakecompany.com/2014/11/the-best-edible-metallic-food-colors/

Thanks @StellaBaking! Looks like Rolkem is a winner :)

I wonder if one greased a bit of acetate, throw them on there and place it round the cake, put a warmish wet cloth around so that the simply stick onto the cake??? You think?

I don't think that would work as you would then have greesed sequins. Another tip to get rid of the loose ones is to blow them off with your airbrush. 

I've just made a 4 Tier Cake with 2 of the Tiers needing the Sprinkles in Gold. No way did it work by painting the Sprinkles straight away. I had to use Edible Glue and leave to dry, plus I managed to get my Sprinkles in Gold which helped out so I would’nt need to use so much Lustre........ how wrong was I. I still used a whole 20g tub of Rolkem Super Gold which to be honest I actually wasn't that impressed with. Nevertheless....I found if I did’nt wait for the Edible Glue to dry, the Sprinkles just fell off which still happened a little even after drying. I need to be extra gentle while painting and used the paint to even stick some of the falling Sprinkles, this actually worked. The finished cake came out amazing but, I would definitely charge more than I did for the cake next time, it took hours to get it just right!