Firewire Compatability

Has anyone tried to connect one of the Yamaha N series mixing boards to Cubase on a computer without a firewire connection via an external PCMCIA or Express card firewire connection? I have a N12 board but my laptop does not have firewire and I have read it is possible to use an external card slot to usb connection. I am wondering however if the drivers would still be compatible and if the audio connection would be reliable.

To clarify I am wondering if this would work:

Yamaha n12 -> firewire cable -> External Expresscard firewire port -> expresscard to usb convertor -> PC