You should absolutely leverage your landscape lights if you have them. Its way easier and cheaper than to use the standard 120V transformer. Your landscape transformer outputs 12V AC. You need 12V DC for the LED. I recommend you get one of these to get the conversion done. It is a very small device so makes it easier to hide. You can get it from Amazon. "72W Outdoor Waterproof Low Voltage Landscape LED Power Supply Converter/Rectifier, Input 12V AC to Output 12V DC"

I just think that the idea of putting the landscape lighting underneath the steps is a brilliant idea. My husband and I are currently remodeling our landscape and we have been trying to figure out what to do with the lighting since there isn't much room for it. We will definitely have to look into putting it under our steps since that would solve the space problem. http://designed-illumination.com/landscape-lighting/