As you can see on the left, the Pew Bible's binding is actually glued to the cover. Usually there's a space between the cover and the actual block of pages which are sewn or glued together (glued in my cheap Bible). Because of this, I had to make an incision and cut the cover away from the binding in order to make a place for my ribbons. If you have to do this be extremely careful. Use a very sharp knife because any tearing or pulling will harm either the cover or the binding, but additionally, be gentle because if you are using a sharp knife any small slip will create an incision in the cover.
As you can see below, I then pried the cover away from the binding with a pencil.
The rest of the project went much the same as Matt's. I applied a small portion of glue to the ribbons and placed them inside the space, spacing them evenly apart. I placed glue on both sides of the ribbons in order to glue the cover back in place. I had to use an even smaller amount of glue than Matt because Gorilla Glue expands 3-4 times. After that I pressed the spine with my Riverside Complete Works of William Shakespeare (both hefty and expendable, only worldly wisdom there, but I include a link to buy it below just in case you're that serious about duplicating the project). The results are below!
Here is the final product in all its home applied, penny pinching glory. Why do I need three ribbons, especially in such a cheap Bible? Well I don't need them per se, but it makes keeping my place a lot easier, and I like to stay in three or four places at once. So, one ribbon for the Old Testament (deep blue), one for the New Testament (silver gray), and one for wherever I need to be besides (lavender). I'm currently using the purple to mark my place for a small group where we read the psalms before praying together. Besides all that, it's worth it for the pure aesthetic value. It makes my Pew Bible more than just a Pew Bible. This method works on plenty of more expensive Bibles, just check out Foolish Galatian or Google the project to see the results of others' work.