Download the textures, and extract them to your desktop. You'll need a program that un-zips compressed files like Winrar, here are links to a couple good ones.
http://ts3cc.forumotion.ca/t288-file-compression-tools
Now, open up Windows Explorer, and go to;
Documents
Electronic Arts
Sims 3 Create a World
User Tool Data
Source TexturesDrag and drop your new textures there.. I have my textures separated into categories for easier access, here's a tut on Organizing your Source textures;
http://ts3cc.forumotion.ca/t281-source-texture-organization
Open Caw, click on the Roads icon, click on Custom Road. Name your road, then click on the first little box on the right for Street Base. Your Source textures folder will pop up, find your new textures and open the folder.
Find the Street_Base and click on it, it should pop up in your Custom Roads Settings box. Now just do this for each texture. Leave the sidewalk opacity blank, unless there is a specific texture for that spot. The program automatically puts in a full opacity if non other is indicated here.
Right click on your new road, and set as active. You'll need to do this each time you exit out of the roads section and come back. This is also where you can edit the road to bring back up the Custom Roads Settings box.
