HP/Compaq does provide service and maintenance manuals for their laptops in that, it shows how to disassemble your laptop. Yours is herehttp://h10025.www1.hp.com/ewfrf/wc/manualCategory?cc=us&dlc=en&lang=en&lc=en&product=453183&
This link is to a picture of your power jack (I hope it's the right one)http://www.amazon.com/COMPAQ-R4000-R4100-R4200-SOCKET/dp/B0062SZFUY
- you'll note on it that there are pins coming out of the bottom. Those pins get soldered directly onto the PCB - there should be no wires to connect and no confusion about the orientation of the part.
Practice your soldering first if you are at all rusty.