Here's a little something to share with everybody, I've got my A4000D surfing the net using the Deneb USB card, OS3.9 and an off-the-shelf PC USB Ethernet device.
Here's the USB Ethernet device I bought for $19.99:
http://www.tigerdirect.com/applications/SearchTools/item-details.asp?EdpNo=443248&CatId=589I plugged it into the Deneb which immediately detected it and mounted it as USBASIXETH.DEVICE unit 0.
Save your USB settings.
Now configure Genesis using the wizard"
Select "Network" for how you plan to connect.
For device enter "usbasixeth.device" and set unit as "0"
Under SANA II configuration select "no"
Don't worry about it not detecting your network address, just manually enter your own (my home network assigns 192.168.0.xxx so I used 192.168.0.110).
Enter your subnet mask (probably 255.255.255.0) and your router address (in my case 192.168.0.1)
Enter your Domain Name Server (DNS) - 192.168.0.1 in my case
Enter your Domain Name ("cablerocket.net" in my case).
Reboot your Amiga and check your Trident prefs and you should see your ethernet adapter up and running. Check Genesis and put the USBASIXETH0 device online if it isn't already. Open your web browser and start surfing!
I hope this helps. :-)