There's a few options fella although you cannot connect a USB mass storage device or a ipod directly to the renault headunit.
- I presume you have a 172, you may or may not have a CD changer under your passenger seat, but in either case you will have a CD changer connector port at the back of the head unit. The CD changer communicates with the head unit via SPDIF digital, so that is a possible point of connection if you use a analogue to SPDIF converter.
- You can buy some very good Alpine headunits these days
http://www.alpine-electronics.co.uk/products/details/digital-media-receiver/ida-x305.html
(I have one of these) which allow you to connect ipods and USB sticks and select the tracks using the headunit controls. You can also get this adapter
http://www.caraudiodirect.co.uk/ict-29-602-steering-stalk-control-adaptor.html
and corresponding piece
http://www.caraudiodirect.co.uk/incartec-alpine-adaptor.html
which allows you to use your stalk controls with an Alpine headunit. There are many other cheaper stalk control adapters available on ebay but this one from CarAudioDirect has two major advantages, 1.) you dont have to dismantle the dash to install it, 2.) It displays relevant information from the headunit of the dash screen, so the dash screen doesn't just go dead.
Hope this is of help.