I did it just like I would install/stretch in a carpet.
Think of it as stretching saran wrap over a bowl, when you're done it should be a consistent tension all around.
Use an electric staple gun, wet the fabric lightly first with a spray bottle (so it'll stretch a bit more and as it dries it should shrink a bit...a tip Mike 'ratter' gave me).
-staple a few inches of the bottom left
-keeping the pattern straight, pull tight and staple a few inches of the top left.
-staple the entire left side. Pull just very lightly, keeping the pattern straight with left top and bottom that are already fastened.
-keeping the pattern straight, stretch and staple a few inches of the right side from the bottom going up.
-staple the entire bottom. Pull just very lightly, keeping the pattern straight with left and right side that are already fastened.
-keeping the pattern straight, stretch the top and fasten working from left to right, stop six inches from the top right corner
-keeping the pattern straight, stretch the right side and fasten working from bottom to top, stop six inches from the top right corner
-pull like heck on the top right corner and staple, try to keep the pattern going up to the corner straight.
-keeping pattern straight, stretch and staple the the last remaining areas of the top and right side.
If the pattern is a little off along an edge when you're done, no big deal...remove the staples from that area, retighten and staple again.
Edit: because I left out a step.