I have very little to add. The letter of the Constitution requires that seven provinces representing 50% of the population, the House of Commons and the Senate must approve a resolution that would introduce such a reform. An additional layer was added after the 1995 referendum, with the legislation on regional vetos, in which the federal Parliament agreed not to pass any resolution without the approval of the various regions. As regards this legislation, Quebec is a region, and that means that its consent would in fact be required, even though, before this act was passed, Quebec's specific consent was not required under the Constitution, in my opinion. This is something that was added during the post-referendum period, when the legislation on regional vetos was passed.
On April 30th, 2008. See this statement in context.