iptables port forwarding

[XLNTech1]

I'm trying to configure IPTABLES to change outbound traffic from 10.1.1.1 to 9.9.9.9:5060 to 9.9.9.9:6060 and then when 9.9.9.9 replies on 6060, convert them back to 5060. I will need to NAT the 10.1.1.1 address to a public IP on the host running tables (I will use 55.1.1.1 as the external on the tables machine). This is VoIP so I will also need to allow UDP for RTP to/from the two hosts involved in the session. A complete session might look like this:

TCP
10.1.1.1:5060 -> 9.9.9.9:5060 translated to 55.1.1.1:5060 -> 9.9.9.9:6060
9.9.9.9:6060 -> 55.1.1.1:6060 translated to 9.9.9.9:6060 -> 10.1.1.1:5060

UDP
No UDP ports need to be translated but the UDP traffic does need to be natted to/from the public ip on in/outbound traffic to/from 9.9.9.9

Any help is appreciated.