Here's one: http://www.chuckhawks.com/controlling_heavy_recoil.htm
Me, I'm not so much into the isometric technique as I am in using a slightly crouched, weight forward stance, with feet about shoulder width apart and your torso at not quite 90 degrees to the target. The idea is to take the recoil down the large muscles of the backside and legs. Even the heaviest recoiling rifles will just rock you back slightly if you use this technique. One proviso - with any heavy recoiling rifle, you'll need to get the butt seated firmly into the meat of your shoulder.
This is not a target shooting stance - you won't take matches with it, but then again if you're shooting matches you're not likely shooting a heavy recoiling rifle.