How would I go about making a texture like Redstone?

Hi! I want to make a textured road decal/block without having to make several different blocks (for ease of use for anyone using my mod), and the way I'm currently going about this is to have an empty asphalt block and a lined asphalt block, the lined block has a top texture that I want to connect to other of the same block like how Redstone does it or how Fence blocks do it (without having it be a fence block), Redstone mainly really. I'm wondering on how I can do this? Or if it is actually possible to do it :P, thanks to anyone replying!