i bought a camera mounting bracket for this very reason, it has a screw thread jobbie on one end with a swivel then the other is a G clap set up, ideal for clamping it to a head rest post i got it from Jessops camera shops (i believe they are all over the country) and cost about £15
ideall you need a camera and a machine with Firewire (IE1394, iLink) to get the footage off as USB is generally too slow...as its done in real time
unsure of what OS yu have, but someone with a mac
will be able to do it with ease as pre-insatlled is iMovie which is ace for video editing