I just tried to get credit for a missed segment on a reroute with the customer service webchat. They were not able to help.

Here is the converstation.

Hello my name is Kate. How may I assist you?
kentb12: Hi Kate, I would like to get milage plan credit for a ticket as purchased but not as flown.
kentb12: I was sent direct from seattle to oakland, when I was booked sea-pdx-oak. May XX, 2006 confirmation code XXXXXX
Kate: Hi Kent.
Kate: You get the credit miles when you actually flew.
Kate: As you have not took the flight we will not be able to credit miles.
kentb12: This happened to me two years ago, and it was made clear that since I was rerouted I would get credit for the flight as booked
Kate: Do you want web purchase credit or flight credit?
kentb12: flight, There already is web purchase credit
Kate: We do not give the credit for the flight which you have not took.
kentb12: I did take the flight, but was routed different
Kate: May I know on which flight number your were routed to?
kentb12: flight 470
Kate: Let me check that.
Kate: May I have your full name, date of birth, mailing address, phone number, e-mail address and the Mileage Plan number?
kentb12: kentb12, ......
Kate: I have checked that the mentioned miles for the flight 470 is already posted.
kentb12: yes, but it was booked differently, and I was supposed to be on 2379 and then 336. I thought it is alaska's policy to allow credit for mileage on your original itinerary or the one as flown, if they are changed. In the past this has never been so difficult to do.
Kate: In order to better handle your situation, please call us at MVP Gold customer service at 1-877-342-5695 during the business hours from 8am-6pm PST, Monday through Friday, excluding Holidays. A representative will be able to assist you.