You can only try to higher treble and presence. Reduce deep near 0.
But with a Herbert you can´t get this distortion that is typical for Randy or ZW sounds. You´ll need a marshall like amp.
Herbert is way to huge. The CT sound is in a totaly different tonal area.
So buy yourself a white Randy Rhoads plexi or a heavy modded JCM 800 2203 with 6550 tubes and a ZW overdrive.