Bleach will eat wool. You can try peroxide, but chances are that you won't get all of it out.
You need to allow about 1 pkg of KA per ounce of wool. So if that sweater is 10 oz, you'd need about 10 pkgs in order to get a fairly solid color. I don't know how much your particular sweater weighs, but the last sweater I weighed was over a pound (16 oz).
If you do not have enough dye, you will wind up with a splotchy dye job. It is always better to have too much dye than not enough, if you're going for a more-or-less solid color.
See what I've been working on at Smetana Dreams
for our new addition expected September 2009