Sharing the ISDN line in WIN 98

i have a 64Kbps ISDN dial up Line, i dial to my ISP from my Win 98. i want all the other systems to use this Win 98 system as gateway to which the ISDN line is connected.
i get a different IP address from my ISP each time i dial my ISP.

How doi make this WIn 98 system to act as a gateway to all other system & share the 64Kbps line ??