You would need an adapter to convert the analog BNC video into a digital equivalent.
You could use a PCI card to maximize compatibility: http://www.newegg.com/Product/Product.aspx?Item=N82E16881127001
or try a simply USB adapted: http://www.dealextreme.com/p/bnc-to-usb-video-converter-cable-40cm-length-51935
google around for BNC to USB or PCI adapters and you'll have a ton of options. This is very possible, as well as cheaply and easily.