fake URL extension for Firefox

[gusl]

From CMU, I can access URLs that I can't from home (e.g. http://psp.sagepub.com/cgi/reprint/33/3/325.pdf ). Sometimes, Firefox will reload when I'm home, losing the information. I'd like to be able to save the files onto my machine, and recognize the URL as that file (essentially a permanent cache). Doesn't Firefox have a lookup table that it uses for string replacement before sending the URL to nameserver? If so, I could add an entry pointing to the URL referring to my local file.

Better yet, find a way to train Firefox on which files are "gated", so that it knows to keep them in the cache forever, unless the user demands otherwise (i.e. answers yes to "Are you sure?").