Phantast, if you are using a gray-scale image as the basis for a model, then the model itself is in Bryce as a terrain. All you have to do to deform the "model" is to alter the height map in the terrain editor (or in your 2D paint program). If each section of the fence is the same gray-scale image, then all that needs to be done is to edit a few sections in order to mess the fence up a bit. Although, I agree, having a simple method to deform a terrain section would be nice. Probably easier done in the 2D program than in Bryce.

Could be worse, could be raining.