Here is the Excel formula:
=CONCATENATE(DEC2HEX(RANDBETWEEN(0,65535),4),"-",DEC2HEX(RANDBETWEEN(0,65535),4),"-",DEC2HEX(RANDBETWEEN(16384,20479),4),"-",DEC2HEX(RANDBETWEEN(32768,49151),4))
Is there any way I can create this random 4 chunk hex code in Access and put it in an update query?