The link for pcsetup2x on that page is dead - but that's the name of the file you need to set up the DOS card. It was released as freeware before that site disappeared, and ISTR an "improved" version floating around too. One note: I believe the drivers will only work with Windows installed: ie, the card won't boot into native mode DOS.

General 630/640 and DOS/PC Compatibility card info:

http://www.lowendmac.com/quadra/lc-630-dos-compatible.shtml

http://www.everymac.com/systems/apple/mac_performa/stats/mac_performa_640cd.html

http://www.edibleapple.com/2009/12/09/blast-from-the-past-a-look-back-at-apples-dos-compatibility-cards/

http://homepage.mac.com/olivers/DOScard/DOScard.html

http://support.apple.com/kb/TA33858

http://www.applefritter.com/node/2042

http://pccardfaq.com/

System 7.6.1 info:

http://main.system7today.com/ (Sorry for wrong name above)

http://www.lowendmac.com/martorana/06/0324.html

Update downloads:

http://main.system7today.com/updates.html