Anyone know where I might be able to rent a Tile Mitre Saw for a day in the Toronto Area? Thanks.

Do you mean a regular wet saw? If so, any equipment rental business or Home Depot Rental has wet saws.

There is no such thing as wet type miter saws that are like the woodworking miter saws. Regular wet tile saws have accessories that allow you to cut angles etc.

Here's one.

http://www.youtube.com/watch?v=J3JiEKkXvyE&feature=related

without a mitre saw how would I cut the edge of my tile to do an outside corner, where I have two pieces of tile meeting at the edge. Would i just grind it freehand, or use a shaping wheel on a normal wet saw. Any easy way to do it?

The DeWalt Water Saw pivots from side to side like for those angle cuts to mitre corners. It works great, but I have never seen one for rent. Without it, I use my grinder to remove material from the back side of the tile. As long as you don't damage the glaze or the face, the joint where the two edges meet (at your mitre) will be filled with grout.