How the heck do you monitor specific EQed frequency in Cubase Artist ? As I recall in PorTools, this feature helps tracking unwanted frequencies by soloing the frequency you’re tracking first, and then cut it off.
If I’m getting your question correctly, you will need an EQ plugin that can do that like the Fabfilter Pro-Q2.
What you are asking for is not really a Cubase feature, but more like a plugin feature that some EQ plugins have.