Bronwyn Webber designed a cake stand for this called the Caddy Wampus system, if you don't want to purchase a stand, on Craftsy, you can purchase the Richard Ruskell Topsy Turvey class for around $40, if they aren't currently having a sale, I believe he uses styrofoam in between his layers and show how to construct, support, etc. For the cake desing Kaysie Lackey has a DVD called the Woodland Wedding cake that shows how to create this design.
I did a white birch wedding cake for my niece and all i did was once covered in fondant i went around the tiers and scored it with a dresden tool in the pattern I wanted then returned to the score marks and "picked" away at the fondant to open it up, once that was finished I used black gel color + vodka to paint the scored marks and open "sores" black.
For this cake I would do the score marks only and to add the knots I would use some extra fondant, shape it then attach it to the sides of the cakes smoothing out the edges to blend, I would start with a light grey fondant as the base then paint it with silver and pearl lustre dusts and painting the inside of the knots with gel colours.
If you are putting the carved heart and initials on the cake just use your dresden tool to carve it into the side of the cake then paint with the black colouring as you did for the score marks.
Hope this helps and here is a pic of my niece's cake