I have never tried to apply for a job at Microsoft but I would think it is very difficult to get a job they are based on its popularity. If I was too give advice on how to get a job at Microsoft I would tell someone to see if they know anybody their first. Also see what jobs are available. Then you might have to take some classes or workshops in order to be qualified for the skills that they need that candidate to have.
Then I was been a great amount of time filling out the application and updating my resume to meet the qualifications and requirements of that specific job. Last I would submit the application and follow it up by calling Microsoft and trying to speak with the human resources department.