I am currently in the process of setting up a Turbocomm PCI ADSL Modem (IA310) under Linux.
The following instructions will have a distinctive Debian feel to them. I do not use any other distribution so unfortunately cannot provide instructions for any other.
The first major problem I have discovered is that the drivers for the IA310 are a binary only module. It is highly unlikely that an open source driver will be released by ITeX (chipset manufacturer) or Turbocomm (they make the IA310). The latest module is compiled for linux-2.4.16 but seems to load correctly under a 2.4.19 kernel.
There are a few HOWTOs out there describing the process and I will list them at the end.
Once I have got it 100% working and fully tested, I will WIKI the process I followed.
One page links to IA310: