Is installing crown molding a DIY project?
It can be done yourself.
What you will need:
Compound Mitre saw.
Drill + countersink bit.
Construction adhesive
Drywall plugs (likely not necessary, but best to have them on hand)
3 step ladders or scaffolding.

You need 3 people.  One in each corner, and one in the center, doing the actual installing.  You will be working with long pieces that break easily, so you'll need to support the work at all times.  

The other problem is getting the material home without breaking it.