Way back in 2006, SPARC put out their 'Author Addendum', a 'legal instrument that modifies the publisher's agreement' for the author to assert various copyrights.
Basically it's a document that is attached to the copyright form usually received by authors that outlines modifications that the author wishes to make.
HOW TO USE THE SPARC AUTHOR ADDENDUM
1. Complete the addendum.
2. Print a copy of the addendum and attach it to your publishing agreement.
3. Note in a cover letter to your publisher that you have included an addendum to the agreement.
4. Mail the addendum with your publishing agreement and a cover letter to your publisher.