Override DNS in Firefox

I'm looking for a way to override DNS entries in Firefox, for development/testing purposes. I know the normal way to do this is via the hosts file, but I cannot edit it since I don't have admin access on my work machine. Does anyone know of a browser plugin/addon which would do this for me?

I did find the SwitchHosts add-on, although it also requires admin rights in order to install itself.

One possibility is to have a socks 5 server on a machine that you have administrative control on, set up this machine as your socks proxy in firefox, and change network.proxy.socks_remote_dns in about:config to true. In theory, all DNS lookups should be done through the proxy, so you should be able to supply your own IP addresses.

Fiddler has such an option: Tools->hosts

If it's just for a few specific requests: the Live HTTP Headers allows for editing HTTP headers and then re-playing the request.

(For other options see also Send Host header when accessing IP address in Firefox on Stack Overflow.)