Well, I've only been using Bryce for 1 week, so don't know the best ways to do things yet, but I made the following image by:

Placing three 2D Faces at angles to each other to make the shape. Created the texture at 512 x 512 in Photoshop. Grouped the three faces and applied the texture.

Then I selected just the top face and using the Edit Texture window shown in message 10 above I set the Y Scale to 300% and the Y offset to 66. Then I selected the middle face and set the Y scale to 300% and the Y offset to 33. Then selected the lower face and set it's Y scale to 300% and left the offset alone.