Photoshop :: How To Color Image With Special Color-layer Under It

I want to color a photo of a brown leather shoe by switching on a color layer under it. I need this because a website script works with 2 separate images/layers. The top layer must be a transparent png of the image (the brown shoe) and the layer under this is a solid color (or more colors). This way you can color a shoe by clicking a button on the webpage.

I tried it using a white shoe on a layer, setting the opacity to 80%, than I used 'Select Color Range' to select the leather of the shoe, than I deleted this selection. This way the shoe keeps the leather look but is kind of transparent. A colored layer under it 'paints' the shoe while you still see the leather texture on it.