Try
http://linmodems.org/
Here is also a
how-to for winmodems.
I had a winmodem woking in the 2.4 kernel. It took quite a bit of reading to get it to work. I have since upgraded to fc2 with the 2.6 kernel. As yet I have not tried to get my winmodem working as I have a spare external modem.
Good luck and keep us posted of your progress.