For audio streams, try eurosport or possibly BBC 5live, they have done in the past and I have used them at work, now we have really draconian restrictions I need to find another office I can work from for 3 weeks with 3G reception! for highlights, most of most stages is quite boring in all honesty, try the ITV Sport site from the UK which I find has the best highlights coverage, or again eurosport. If you can understand any of the main western european languages there will be all kinds of choice. I would guess Cycling TV will be charging for coverage, but if you don't mind diping in your pocket then they are possibly your best bet -email them and ask.

watching it Live???? - as in front of a TV and eurosport for 3 weeks, or actually standing on a mountain somewhere - if it's the latter then lucky lucky you, and tell us more.