How to get a teen to cooperate with identifying and treating possible ADHD?

Our 9-year-old daughter was recently officilly diagnosed with ADHD.

Our 15-year-old son has long had problems at home and school that fit ADHD:

-failure to turn in assignments

-playing video games or watching when he should be doing homework--he does this while we are in the same room!  We walk by, catch him, and he denies it.  Then we catch him again.  And again.

-frequently interrupting speakers, including my wife and me

-impulsivity and poor decisions

-lying about things that he can not possible get away with--"Did you start the laundry?"

-Refusing to do chores

-Great difficulty getting out of bed--we often run late getting to work and have sometimes had to force him to walk to school after we left.  Once, the school had to call the police to collect him around noon.

-Difficutly sleeping at appropriate times, but falling asleep an inappropriate times

-Blurting out mean things or things that will get him into trouble

-Lack of respect for our privacy

-"Discovering" things I have already told him.  "The Griffon coaster stops at the top of the hill before it drops you!  Loch Ness Monster has interlocking loops!"

-Not learning from past mistakes or consequences

A big problem is that he has refused to cooperate with therapists.  He winds up going into the session and just saying everything is fine.  (It is hard to believe, but he doesn't mention the fights with his mother.)  We doubt he will cooperate with medication.  But I don't think there will be substantial progress until we try to treat the underlying issues.  (He already has an academic plan at school, but not specifically addressing ADHD.)

A big complication is that I believe my wife has ADHD.  So consequences are not evenly enforced.  Sometimes, she will shoot right to the biggest consquence ("Then you can't go to camp this summer!") and then have no more cards left to play.  But he does go to camp, of course.  Sometimes the punishment is no videogames for the day.  After hours of me resisting his nudging to let him play, she decides to let him play without discussing it with me.

The ADHD also leads to her having extreme swings about him.  She recently told me how much better he is doing in school this year.  I cautioned her to not get her hopes up to high.  Sure enough, she found out he did not make up a science test and has a 30 in the class.  This was followed by a HUGE explosion and argument between them.  She'll also expect too much, too soon.  I try to focus on get the work done and turn it in, even if it is not going to get an A.  Even when she tries to support this, however, my wife will always had that she KNOWS he can get As.

Back when I was struggling with my doctoral dissertation, my wife thought she was helping by telling me that she KNEW that I was going to finish it.  I told her that what I needed was A empathy and validation of my feelings ("I can see why your so discouraged when you have so much farther to go and it is taking longer than you expected") and B recognition that I MIGHT NOT BE ABLE to finish it unless she changed some of her behavior (such as calling me several times in a row while I was trying to work or asking me to run errands because she forgot something.)  Telling me she knew that I was going to finish it meant added pressure on me--I was really going to disappoint her!  If it was so easy, then I must really be a screw-up if I didn't finish it!  During this time I had what I call "the bus fantasy."  The idea was simple:  If I got hit by a bus crossing the street, I would surely have an excuse for not finishing and no one would look down upon me as a failure.  

She has recently told me that she believes our daughter is "faking" or "exaggerating" some of her anxiety symptoms in order to get attention.  OMG, I thought, how are we ever going to solve these problems if my wife refuses to believe that they are real?  If she is just trying to get attention, then why not punish or shame her so she will "learn her lesson"?  If we believe that she is truly having anxiety attacks, then we can get medical treatment and try to work with her in different ways than yelling and threatening punishments.  The fact of the matter is that she has not "learned her lesson" from consequences and punishment.