Step 1 - Get Mom's Attention. Sit on the arm of the chair while she's working on the laptop and stare at her with big blue eyes until she can't stand it anymore.
Step 2 - Once she has decided you're not going to give up, she'll help you get into the sweet spot between the computer and the arm. This spot is very comfortable for sleeping and Mom will even pet you while she is working on the computer.
Step 3 - After a while you may need to get her total attention because she's too busy with the computer and not petting you enough. Get up and crawl onto her chest where she can't ignore you. This will get you the best petting time.