Hi ShrewGlue,
The UVs for your DM are going to be setup based on the original meshes UVs before the DM was created. Control the UV for the base exterior of the mesh can be handled via the method that UDKAP mentions.
If you need to adjust the interior UVs, you can do this by opening your mesh in the fracture tool > Fracture Settings > General > Fracture Material Desc > UV Scale > adjust the values here for the X and Y to get more or less tiling for the interior pieces, if needed.
Thanks!
Tim