PrPixel,
Your friend probably removed his Tivo hard drive and placed it in one of the bays of his PC, then used 3rd party software to make the transfer. There are some similar hacks for the Mac, but they involve going root and getting into the Unix terminal.
I use a little box called the Canopus ADVC100 which takes the analog output of the Tivo and has a codec for translating it into digital. From there, it's a Firewire hookup to my Apple Cube right into iMovie. I stitch everything together, set the chapter indeces[?], find some nice frame grabs for the DVD menu, then transfer it to iDVD and finish the DVD. Have a look at it here:
http://www.canopus.us/US/products/ADVC-100/pm_advc-100.asp
I've compared the Tivo/iDVDs I've made on my Mac against the original digital video on my Tivo and it's very acceptable. The loss in sharpness is 5% at the most. There is a noticeable loss in overall color saturation, but if you don't compare them side by side, it almost doesn't matter.
It's a really nice little unit and the audio and video never get out of sync like some of the other similar boxes.
Something to look into maybe? Heheh
Dean