If you hacked the ditto snippet, as described in the instructions, you only need to do a few more things.
Create a TV called m3_tplBox with an input type of "Text" and a default content of m3_su_BlueBorder (or whatever chunk name represents the box color you will use most often). Make sure you check the box that assigns this TV to your site template you are using!
Edit the default content of the TV called "m3_rightContainer" and add this to the Ditto call that should already be in there:
Then create a chunk that will serve as the template for the color you want. In the zip file included in this post, I have created these chunks for you. You have Blue, BlueBorder, Orange, OrangeBorder, Green, GreenBorder, Grey, and GreyBorder. So paste the contents of any or all of those into new chunks.
Then when editing the document that represents the box, you should see a TV with the default content of m3_su_BlueBorder, and you can change this to the chunk name that represents the other color templates, to override the default box template on the individual document basis.
Hope that wasn’t too confusing :-D