You can also use the free software from ETI to create an IMP ebook. There is a link on the eBookwise site. The ETI software is more powerful. The Librarian software is slightly easier to use. When I had my eBookwise 1150, I used the ETI software to create ebooks and the Librarian software to upload them via USB. The Librarian software can be used for uploading, even after the 30 day demo period has expired (only three ebooks at a time, though).
For more information on conversion and other methods to convert documents to IMP, see
http://www.chromakinetics.com/REB1200/index.html