The TNT already has a route to the IP pool. You do not need to manually enter a static route of any kind in the TNT. However, you need to make sure your default gateway router has a route. Having a route on the switch is not enough. If it is indeed a switch and not a router it won't help. Your Internet router needs to have the route otherwise it will think your IP pool addresses are out on the Internet somewhere.
To help, what is the IP address range of your pool? What is the IP and mask of your TNT? What is the IP and mask of your Internet router? Am I correct in my previous assumption in that you basically have a TNT for dialup and another Cisco or some other router for Internet access? For example:
Dialup user <--t1--> TNT <--enet--> Gateway Router <--enet/t1--> Internet
I am not concerned with switches or hubs since they are basically dumb and don't really do any routing per se. It is the Gateway router that has the intelligence to know how to route to the IP pools on the TNT.
Hope this helps.