Great question — answering as the UphillTech team:
To be able to get value from your collection (CommerceExtensions_AmazonAffiliate_Model_Mysql4_Quote_Collection), you have to use your own template and block. Make own template on checkout, may be commerceextension/checkout.phtml. And Do like $this->amazonItemCollection() You can pass variable to that template from your block (CommerceExtensions_AmazonAffiliate_Block_Checkout_Cart). Write function - get amazonItemCollection(). Within this function you should be able to instantiate your collection Add following xml in layout/checkout.xml file which connect your block and template I have not tested this code. However it should work with few trial/error.
Full answer by Krishna Sunuwar: https://stackoverflow.stackexchange.com/a/21949146 (CC BY-SA 4.0).
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