I've made it but I did not try piping. It is very soft. The petals would probably hold their shape but the cone base would probably not hold up. You could probably do roses on hershy kisses or make the cone out of fondant then pipe the petals on. I would refrigerate or freeze the roses before trying to transfer them to the cake b/c they obviously won't crust and would smoosh when you tried to handle them. Good luck and let us know how it turns out.
Haven't used her recipe specifically, and I use SMBC, but the answer to you should still be the same. I pipe roses with mine all the time. I use the witch's hat rose nail so there is no need for a base, but if you wanted to do one the icing would need to be colder (and therefore thicker) than normal or you could do all the bases then chill them. I usually put the roses directly on the cake but if I need to make them ahead or if they are needing to go on the side of the cake, I set them on waxed paper and freeze em first. Just make sure you only pull out a couple at a time and don't hold them long. All that butter melts fast 
I have my own recipe for IMBC and yes you can pipe with it. Fill 2 bags and pop one in the frig. Alternate them as your hand warms up the bag. Don't chill it too long though or it'll be as hard as a rock!
Jacqui
Thanks everyone for the advice!
I made Elisa's IMBC today and it was good. For some reason though, once I added the butter it was in a liquid form and I had to stick it in the fridge to get stiff again. I piped a few shells and stars with it and it came out ok.
The only problem with it is that it doesn't crust and I couldn't really get it smooth with the spatula.
BTW, I made Elisa's Chocolate Cake recipe, soooo dry! I followed it to the T and it was the driest cake I've ever had.
A couple of things with IMBC. Make sure your butter is not too warm. You should be able to squeeze it and it should still be a little firm but not refrigerator firm. The next thing is after you add your butter you should have to whip it for another 5 minutes. It'll be loose at first, and may look curdled as you continue but keep going until you reach a smooth creamy consistancy. No, it doesn't crust but it's so smooth and silky on your tongue! I use a scraper (you can get it in the paint department at Home Depot or Lowes) and apply my BC heavily and then take it off with the scraper. I also read where a gal refrigerates her cake till firm and then takes parchment paper and her fondant smoother and smooths it that way. I haven't tried it yet but I'm going to next time. Too bad about the recipe. Try the Double chocolate layer cake on Epicurious. I think it's posted in the recipes section here too. I love it! It's moist and chocolaty!
Jacqui
metal so that you can use heat to melt it smooth. Mine is 6" and I haven't made any teirs higher than that so it works fine for me.
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