Ports are not part the "normal" DNS system. There's no way to add a port to a A or CNAME record.
Side Note: Some software supports SRV records which do include a port number. This is very uncommon and I don't know of any web browsers which support this (which is probably what you're asking about).
If the websites are one the same machine, you can use host headers to differentiate. I'm guessing you've got Dynamics CRM installed; which defaults to port 5555; you can add an additional binding in IIS for port 80 with a specific host header.
If they're on different machines, you can use a reverse proxy to send traffic to each machine as is appropriate. ISA Server or Forefront TMG can do this; or there's dedicated devices, alternates like HAProxy, Squid, etc, etc.