I don't have any answers although I do understand what you are going through. My son is similar. He can't seem to remember simple things. Just yesterday, I sent him to brush his teeth an went to check on him and he was in the shower! I asked what he was doing and he said "you told me to take a shower". I said, no, you were supposed to brush your teeth, you've already had a shower. Oh, he said, that's right, I am supposed to be brushing my teeth.

Have you tried fish oil as a supplement? That seemed to help a little. We are looking at Neurofeedback Therapy so you might check into that. There was a discussion a while back about it:
http://giftedissues.davidsongifted.org/BB/ubbthreads.php/topics/145803/1.html.

I don't know anything about Cogmed or Pace so I'm not much help. Hang in there.

What I am is good enough, if I would only be it openly. ~Carl Rogers