Is there a function for getting a rod, dread, or brush sound on a closed hi-hat?

There's not.

But one thing you might try doing to create an essence of this is to raise the attack knob. Essentially, this will case the shortness of your attacks to ramp into each attack, giving it a softer sound. It won't be literal, but can definitely give you a change in the normal sound, and imply your intentions.

If you need to program this into a score so it's adjusted automatically as your file plays back, use midi controller #26 (CC26). Value all the way up would be 127. Value all the way down (default) is 1.