How to process a cube in a SQL Agent job
It can be done but it's not well documented and it's complicated by the fact that you can't easily get the result of the process. Unless you actively check and manually raise an error if there's been a problem, the job will report sucess no matter how screwed up the cube processing is. That part is all about the XML results that are output by the process.
Here's how I do it (and I'd be very interested if you have any suggestions to improve it):