manually adding stuff to feed…

is there a file i can edit to add items from a different feed to my wordpress feed?
specifically, i want to add the items from http://www.ElNacho.com/rrr.xml to http://RamblingRetardRampage.ElNacho.com/category/podcast/feed
or to http://RamblingRetardRampage.ElNacho.com/feed/

is there a way i can do this without just making a bunch of posts in WordPress?