how can I use 2+ boards at the same time?

hello,
 
       I download the newest version of bttv driver(0.7.78,use v4l,not v4l2),I have 4 bt878 boards in my computer,how can I use these 4 boards in my computer via v4l api at the same time,according to you document,your driver can do it,but I don't know how to use at the same time ,I need you help.
        Hope to hear from you eagerly,thanks,thanks,thanks,I am in urgent situation