Absolutely! When you use the "create a new project" page, at the classification question you would simply have to select "book". When it comes to uploading files, itchio already accepts .txt, .pdf, .epub and I'm sure many other types of files as well. You shouldn't encounter any particular problem, but don't hesitate to ask a few more questions if you encounter problems with the upload page's interface.
Then, to submit your project as part of the jam, once it is uploaded go back to the jam's main page, click on the "submit your project" button and select it in the list.
If I've been unclear let me know!