icing?

I have extra stiff royal icing and i have to cover a cake with brush embroidery technique and in the past I used just buttercream to do that technique. Am I able to use royal icing just the same? I just don't want to make a batch of buttercream if I don't have to tonight. I have to cover the top and sides of a two tiered cake that is covered in fondant and wondered when the royal icing dried would it pick off (or dry off).
Please let me know asap if you can? It's a all-nighter job tonight! Here's what I have so far. I have to move cake to smaller circle as way (that story is for another post).

Susan, no worries!

In March I had a class with Collette Peters. That is how she taught us, fondant covered cake and royal brushed embroidery.

thanks so much. Now it's 10pm and I'm going to get moving on the cake. It's been sitting around like that all day while I waited for the customer to tell me what she wants. She first wanted it painted and then brush embroidered instead which is easier for me. She wants the flowers off the cupcakes though and just one or two seashells on it. I don't mind changing because she is paying for everything I made so far and for the changes and I have time to work on it tonight. I want her to LOVE the end results.

thanks again for your quick reply

Add a TINY amount of piping gel to the royal - it will be much easier to work with for brush embroidery.

I made the cake and will be posting it on my photos soon. Thanks again everyone. This is the final cake that I will post here too.