Date Range in URL

Hi,
I want to have a date range in my URL, such as /charges/
from/:from_year/:from_month/:from_day/to/:to_year/:to_month/:to_day

I want to have two date selection controls on a form, and when the
form is submitted, I would like to be taken to the appropriate URL,
such as /charges/from/2007/01/01/to/2007/12/31

The problem is, I don't know what options to pass date_select in order
to have the params generated match those shown in my route.

Any help is appreciated!