Alpha texture overlaying opaque texture, both with colors?

I've been trying to find a shader that has the following features:

• 2 textures

• 2 colors, each for one texture

• the second color has to support alpha (as a .png picture) and overlay the first one

• I must be able to set a color to each texture

I've found this shader that does exactly I what I want, but doesn't let me apply colors to the textures: http://answers.unity3d.com/questions/544230/trying-to-write-a-simple-mixing-2-textures-shader.html

I'm trying to do this because the player should be able to pick a shirt pattern and 2 colors. The first color will be applied to the first layer and the second color to the second layer, which is a .png picture with an alpha channel representing the shirt pattern.