Connecting to a remote computer via the internet. The host computer does not have a router only a cable modem

[Gil Bertin]

To whom it may concern:

I need to administer a remote computer via the internet. The remote computer
does not have a router. The remote computer has a broadband connection. Is
there a way I can enable the port range connection (i.e. 5900 TCP/UDP) on
the host computer even though they do not have a router. The OS on the
remote computer has XP Pro. Do I need to do something in the registry or in
DOS?  PS: On my end I have a linksys router. Please advise.

Thanks