1. Clone and prepare the repo:

   $ git clone https://github.com/google/material-design-lite.git
   $ cd material-design-lite
   $ npm install
   $ sudo npm install -g gulp  # needed to build

2. Set your colors in src/src/material-design-lite.scss, BEFORE the @import "variables"; line.
   The colours must be in "R,G,B" format (values 0-255).
   Example:

   [snip]
   /* Material Design Lite */
   
   // Customisation: add these varibles here
   $color-primary:      "7,54,66"   !default;
   $color-primary-dark: "0,43,54"   !default;
   $color-accent:       "133,153,0" !default;
   // You can also set these:
   // color-primary-contrast 
   // color-accent-contrast
   
   // Variables and mixins
   @import "variables";
   @import "mixins";
   [snip]

3. Build and use it

   $ gulp
   $ cp -a dist/* path/to/your/website/assets