I have just experimented with stenciling from stencils I bought from Lindy's cakes and it was extremely difficult attaching it onto the sides of the cake. In the packet it mentions for you to dab a bit of royal icing onto the ends or to wet it with some water and stick it onto your sugarpasted cake but when I tried to do this it kept on coming off (even before I started to smear the icing over it). There was also the problem of the stencil being too high for the cake. I sorted this problem out by placing the cake onto a turn table on the edge and placing the stencil starting from the turntable. I have watched the video on this site on stenciling and it mentions cutting the edge of the stencil with scissors but I didn't want to ruin it. Is there any other way?
I got my stencils from Michaels (hatbox on top of suitcase in my pics), I cut it to size and it was only like 3.00 so I didnt feel bad cutting it. Most of your cakes will be 4 inches high anyways so I wouldnt cut it smaller than that. As far as attaching it, I did what the video showed and held one end as I went across with the icing, I didnt attach it with anything. I think it just takes practice. Try doing the sides of your cake pan or the side of a box til you get the hang of it.