Start here:
http://www.cssd.ab.ca/default.asp?V_ITEM_ID=1774 It contains the names of the people you need to speak to.
First, are you guys catholic? If so, you should be able to get in with a little persistence.
Talk to the principal first, then the superintendent, and then the trustee as a last resort. A sob story about only having one vehicle and you feel it is not safe to bus your 5 year old that far (because it isn't) will help as well. Make sure you are on the waiting list because lots of people move, go to public school, etc.