Unfortunately, I'm not aware of any all-in-one easy solution on the Mac. (but neither have I had use for one on Windows either)
But perhaps the publisher software from the manufacturer's website will be useful enough for your niece to create/edit documents/books (for Mac OS X):
http://www.ebooktechnologies.com/sup...r_download.htm
Once they are created it's simply a matter of drag-and-drop on the memory card used with the 1150 (using a USB cardreader)
The more technical solution might be the use of Parallels to run Windows (very well!) on an Intel Mac (
http://www.parallels.com/en/products/desktop/)
P.