Ummm, The sound card software is not made to work through a hardware modem, but with the sound card connected to the radio through an interface.
here are a few links for you to look at.
http://www.tigertronics.com/http://www.westmountainradio.com/http://www.packetradio.com/http://www.mfjenterprises.com/products.php?catid=10check the links out and if you need some help I am sure there are quite a few guys that will be willing to help you.
Good luck
Gary n2vww