I don't know if C4D has subD modeling but if it does, that would be a good way to proceed. The shoe here (http://www.plazadelpixo.com/miscellaneous.html - 2nd row 3rd from the right) was made using Modo's subD modeling and it worked pretty well. Good luck.
Hi Lara,
the attached youtube link may help.http://www.youtube.com/watch?v=tIEW_yy7Kaw
I worked thro it first then attempted the boot from your link.
The attached photo's show the result.
Barry