New firmware (24!)ftp://ftp2.zyxel.com/VMG8924-B10A/firmware/
Flashing the latest v.20 firmware, with an Eircom header, in effect unlocks the F1000. When the v.21 firmware is released, the F1000 should accept it. No need to open the router and do the unlock procedure.
@RTouris and welcome to the forum !