hello again,

upon checking further into the Compaq support site

this userguide

http://h10032.www1.hp.com/ctg/Manual/c00530488.pdf

seems to have instructions for replacing the RTC battery (aka CMOS battery)!!


Check the userguide, page 124.
From what ive scanned, you might have to remove the ram modules, then remove the wireless card, and underneath should be the RTC (cmos) battery.

The main page on the Compaq website that has this manual is here:
Manuals for Compaq Presario V4000 Notebook PC - HP Customer Care (United States - English)

Goodluck again!