How do you sell books on Chegg.com?  

Selling textbooks is always tricky. Most school buybacks and most buyback websites won't buy a book from you if they already have a full stock of that book, or if a new edition of the book has come out. With new editions coming out on a regular basis for most textbooks, this can make it really difficult to sell your books directly to a bookstore or book website. You might have more luck with a site like Amazon or Half.com where you sell your books directly to other site users. I personally recommend Amazon, because while Half.com has good policies to protect buyers, they do not do so well at protecting sellers.
I always understood that Chegg.com rented out textbooks rather than selling them, so it seems a little strange to me that they would buy used textbooks. It's possible you got faulty information.

I'm really curious what magazine it was that said that. As far as I know, Chegg.com has never purchased anything other than used textbooks. They can be pretty picky about which textbooks they will purchase; you won't have much luck unless the ones you have are the latest editions available.

One site you might try is http://www.cash4books.net/ A few myLot members have said it's pretty good, and they had their payment for the books they sold within a week. They seem to mostly take books that have been released within the last 5 years. If you've got some books that are older than that, you might want to try trading them for credits on PaperBackSwap.com. You'll have to pay for media mail shipping to send the book to the recipient, but you'll get a credit that you can use to get a new book basically for free.

No I personally have not. I know some friends who have though. I've heard they have decent deals but you have to make sure it's the product you want. Decent website. I think i'll check it out later