Kindle Rental Textbook

Is there a way that you can keep your Kindle Rented Textbooks? I understand that one can remove the DRM from already purchased books.. but what about rentals? Thanks!
Answer #1
Not sure if any of these apply to you, but there worth reading real quick
http://www.the-digital-reader.com/2012/06/15/how-add-kindle-drm-removal-plugin-calibre/#.URZg_qUaZXE
http://www.scribd.com/doc/56596589/Converting-Kindle-Books-a-Painful-Process-That-Works-for-Reading-Kindle-Books-Without-a-Kindle-Nyquil
http://librarianbyday.net/2011/10/26/how-to-extend-the-due-date-of-your-library-ebook-on-the-kindle/
alby