If you have a newer Tivo connected to your network you can browse the Olympics Guru guide by sport and get season passes to whatever you want. But like Otto said it will record full blocks, which can be 8 hours long so be prepared for lots of fast forwarding. Just make sure you have lots of hard drive space especially if you record anything in HD. It's amazing how fast 8 hour blocks of HD content can fill your hard drive.
This is going to be a big help, and mine should be here before the end of the week.
Western Digital 500GB My DVR Expander eSATA External Hard Drive - WDG1S5000VN - Buy.com
BTW, the price went up $25 since I ordered 2 days ago. I guess the olympics is really creating a demand for these.