What about the "dial whenever a network connection is not present"
that should mean that if your cross-over network cable is plugged in [to the Empeg] then the PC won't dial out.

It will also mean it won't dial if the empeg is online and you want to read your mail though, so that may make it a non-starter.

And if you have a hub then the network connection is always there too.
But what are doing dialling up for if you have a LAN connection?