It is possible to craft jacketed wires using any material, aside from glass, that can be cut into pieces or cover plates. Examples of jacketing materials cover a wide range from Cobblestone to Netherrack to Pumpkins to all colors of Wool, and allow your cables to more readily blend into your building design. Any Jacketed Wire will connect to any other Jacketed Wire regardless of covering.
For further blending in, you can use your wires in conjunction with Micro Blocks. All redpower wires can travel between two cover blocks on the same square. You can also craft a Hollow Block out of eight Covers in a square on the crafting table and place your Jacketed Wires inside of these hollow blocks. Combining these two methods means you can have your wires literally running through the inside of your walls, and it would look completely flush and normal.