How can I make my router connect to the internet through a computer?

1. Set up sharing on COMPUTER with 3G
2. Set up static ip address on COMPUTER with 3G (192.168.5.1 or so)
3. Connect your COMPUTER with 3G to WAN port on ROUTER
4. Set up static ip address on WAN settings with GATEWAY pointing to 192.168.5.1 - Ip address from range 192.168.5.X), as DNS servers you could use some google servers 8.8.8.8, 8.8.4.4
5. Enjoy :-) As long as you've shared your connection on COMPUTER properly you should be fine.

You need to enable some kind of Internet Connection sharing feature on the computer with the Internet connection. You haven't stated what OS you're using, so better details will be harder to give.

Here's some potentially helpful links:

• Internet Connection Sharing for Windows XP (and previous)
• Internet Connection Sharing for Windows Vista/7
• Internet Connection Sharing for OSX 10.5
• Internet Connection Sharing for Ubuntu Linux