You should be able to use your router to redirect port 80 traffic to 8080. If your incoming port 80 traffic is being blocked by your ISP then there's other things you need to do.
Depending on what DNS you are using you should be able to redirect with that. If you are just using an IP address followed by the port then you are out of luck. For example, No-IP will let you redirect port 80 traffic. http://www.no-ip.com/support/guides/web_servers/isp_block_port_80.html