You can!  Just keep in mind that it can be a little tricker to pipe than buttercream and is much easier to pipe when it is colder.  One trick is to transfer to a piping bag just after you have gotten it light and fluffy, then store in the fridge for just about 20-30 minutes to chill back up a bit.  This way, it should still be smooth and creamy but hold its shape a bit better.