Since there is polipo in the ressources may be, i'll use that for the moment (and will turn back later on privoxy - which i prefer either as passing proxy or as filtering proxy, where it does really a great job!).
Btw, sometimes i even used both together in this way: polipo (as caching proxy, which allows to turn off completely the browser's caching, either ram or hd) > privoxy as filtering proxy > tor as socks proxy