I've heard of people doing this but I don't know how.

The book is Bernie's White Chicken and I can't locate an ISBN for it. I've heard that it has been re-published in recent years but I'm not finding anything.

I did find an ASIN on amazon.com. But that didn't help any.

http://books.google.com/books?id=exADAAAAYAAJ&pg=RA1-PA302&lpg=RA1-PA302&dq=%22bernie's+white+chicken%22&source=web&ots=VjGzfgnTFY&sig=sEDrvIxxoheRCdmK98kg7QWw7gg

I looked for you too.  I couldn't find anything...although I did see a couple places where you can buy it.  It looks like it was originally published in 1874, so it is probably out of print.

I'm not sure of how to post wishlist books if they are not in the system and don't have an ISBN.

you will probably have to create the book and I believe if a similar book is posted with the same name and author (if someone posts a book and creates another user ISBN) then it should notify you that another book has been posted that is similar to the one you have

It has been republished, I found a copy here

http://www.keepersofthefaith.com/Catalog/PageClasses/PictureDisplay.asp?PicNumber=SM3215.jpg

but I can't locate an ISBN there. Maybe I'll try Leslie's suggestion of creating a page for it.

If it doesn't have an ISBN the WL will not pick up your wish even if a book with the same title is posted. Read the Help Center on the WL and it will tell you about non-ISBN books and the WL and the fact that it doesn't do any good to list them on your WL since you will not get a notification if it is listed. Frustrating, but true :(

Here's the HC link: How do I add a book that is not in the database to my Wish List?