If you're very good with mitre saw skills, go ahead with this. You may need help to support molding while you nail it in place.
In my opinion, easy. Check these sites out and see for yourself.
Personally, I find that very daunting, first because I cannot cut a miter cut for the corners to save my life, and second, doing so much work over my head that requires you to have your arms up a lot. Having someone to help who had done it before would be really beneficial. Perhaps if you search through You Tube, you can see how others tackle it.
What other Hometalkers did.