Netbios over IPX/SPX

Our company uses a DOS base application from service bureau to maintain records. We access the system over IPX/SPX gateway on site. We currently use NTserver 4.0 on site as NOS. Also, we use client boxes with W98 and W95. I am phasing out W95 and W98 with WinNT 4.0 Workstations. To enable W98 and W95 boxes we must install IPX/SPX compatible protocol and enable Netbios over IPX/SPX. Works ok on W95 and W98. Problem is in NT Workstation. How do I enable Netbios over IPX/SPX on NT4.0 workstation to be able to successfully establish connection to Gateway and off-site server? The Gateway appears to be the problem.