The proof of claim form and instructions about how to fill it out are located at http://www.uscourts.gov/uscourts/RulesAndPolicies/rules/BK_Forms_Current/B_010.pdf. It is possible that an attorney is representing all of the retirees (or if you get a group together, you may collectively be able to hire one).
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It can't be "protected from" the Chapter 11--the company has a fixed amount of assets to pay out with; the nature of an 11 is that someone pays this to take the assets.
It is possible that a counsel will be appointed to represent the interests of retirees at the estate's expense; it may be necessary for someone to take the initiative on making this happen.