Can't use DYNDNS domain at home, so can I use DNSMASQ to redirect domain and ports?

I have comcast internet service and I use DYNDNS to provide a domain. We have a couple of IP cameras that are on different ports, so the router can forward traffic to the right internal IP address... so MYDOMAIN.ORG:88 forwards to 10.0.0.22:88 and MYDOMAIN.ORG:89 forwards to 10.0.0.23:89 

While this work well externally, when I'm home COMCAST doesn't seem to let me loop back to my router, so I was thinking of using DNSMASQ if I could to capture all internal MYDOMAIN requests and forward them to the right IP and port on the internal network. 

I see how easy it is to use names within TOMATO, so I can name 10.0.021 MYIPCAM1 and have tomato send traffic to the right IP address.  BUT, I can't find anything that would let me use the same MYDOMAIN.ORG internally and have Tomato or DNSMASQ redirect to the right internal IP and port. 

Hope this is clear.  Can this be done?

M.