Don't take this the wrong way, but if you have to ask even with the information and pictures that have been given, this project may be a bit over your head.
I know Prim has a boot guy (he has a guy for everything! :lol ) that I believe will be doing the modification to his Free Runs.
The short-and-sweet of it:
1. Make a faux boot upper (out of the material of your choice, preferably leather) in a similar fashion to those that can be seen on adult-sized "Halloween Store bagged costumes". Like this.
http://www.cappelsinc.com/product_images/catalog19950/25166_Boot_Tops2.jpg
2. Have a cobbler sew this to the Free Run 2, just above where the outsole meets the upper... seen here.
http://i14.photobucket.com/albums/a332/Primrodo/Green Arrow/Arrow/ArrowBoots.jpg
Optional:
1. Commission someone to do all of the above.
2. Find a "close-enough" alternative.