Although in 11.0.4.1 and 11.0.4.2 IX Workplace can show the Feature Manager button, you cannot change the hunt group enable/disable (unless you have a physical phone associated with the IX Workplace).
In R11.1.0, Hunt Group enable / disable can be set by IX Workplace (with or without an associated physical deskphone). Once you ticked "Can Change Membership" (see my post above), the Feature Manager button appears automatically on the IX Workplace client.
IX Workplace Feature Manager hunt group control is officially supported in R11.1.