An e-petition will require 5 citizens/residents and an MP to be created. Once it is approved the petition can start collecting signatures. A minimum of 500 signatures is required to have the petition presented to the House of Commons.
Perhaps organization such as Fair Vote Canada can draft the petition and find an MP who will be willing to sponsor it (most likely a Liberal, Green or NDP MP). I will be willing to put my name forward if Fair Vote Canada can't find 5 citizens to start the petition (but I am sure they can).
Thanks for jogging my memory. I believe I was one of those 360K Canadians and I was excited about proportional (I believe it was called ranking ballots back then?). Now, the interest in proportional vote may or may not have changed among Canadians after 8 years but it's worth investigating by organization such as Fairvote Canada.