You can try to inform him during recruiting, which will guarantee that he will accept it. Costs a little more to recruit a player like this, but it's a 100% guarantee that he'll take the redshirt.
Or, you can try to redshirt a player and sometimes he'll simply accept the redshirt, no questions asked, without a WE drop.
Or, a third option is, try to redshirt a player and if his WE drops, remove the redshirt. His WE will return to normal. Then, try to redshirt the same player. Sometimes he'll take it on the second attempt, many times he won't. You can continue this indefinitely, but "usually" if he doesn't take the redshirt after about the fourth or fifth attempt, he's not gonna accept it. There have been instances where a player has, but they are kind of rare by that point.
There may be other ways, but it's getting late and this was what I came up with right off the top of my head. Furry is good at stuff like this, he may be able to tell you some other methods that may work.