UE4 - How to edit the shape of a Decal Component?

Hi, i added a decal component to my BP, and it has a box shape, but this is giving me some problems because the mesh in this BP its actually cilindrical and i want the decal component to cover it but not go farther than the cylinder edge, but the Decal Component has Little options, and you can only set it to box shape, how can i edit it to make it as a cylinder?