I have two 486 NEC Laptops (PC-460-1541 (DX4) and PC-450-1541 (DX2)) that I'd like to replace the CMOS battery in as otherwise they work great with DOS and Windows 3.1.

Anyone know how to go about changing the CMOS battery on these? Havent taken one apart before and cant seem to find any documentation on how to do it...