If you wish to acknowledge all alarms of a certain type (for example, all those belonging to a certain Area), you may use the Alarm Manager's called AckFilter variable, which allows the user to execute a filtered AckAll.
This does not override the alarm panel's Ack All button; rather, you must create your own button that triggers a script to set the AckFilter variable. When the Alarm Manager sees the AckFilter variable go valid, it copies the filter, starts executing the necessary steps to acknowledge all alarms that fit the criteria of the filter, and sets the AckFilter variable back to Invalid.