I have pics for the IQ526 and they use the same motherboard. It's a really simple job once you really get down to it. First remove the USB device for the wireless keyboard and mouse(It's not good if you don't take it out now. Personal experience.) Lock the rear support all the way out, take out the screw on the small panel on the middle of the back and slide it down and off, then take out the 4 screws holding the support on. Next take out all of the visible screws on the back panel. There should also be 3 inside the cable bay on the right side(when facing the back panel), 1 facing toward you and 2 you'll have to get from the side(they're next to all of the plugs). There are 2 on the left side under the small cover for the BD/DVD slot. That cover comes off easily. Just slide a small screw driver under the bottom edge carefully and pry it out and you'll be able to see and access the 2 screws. After the screws are out, gently pry up at the bottom of the rear panel and pop the panel out. It's not too difficult a process but definitely one you want to be careful with because you definitely don't want to mess up the back casing. After the casing is off there is a metal panel in the middle with a hole in it to access the RAM modules. Take out the screws all the way around this panel and take it off. No prying necessary this time. Sometimes there is a piece of tape at the bottom but it's not an issue because it's not really doing anything except keeping out a minimal amount of dust. Once the panel is off, there are 4 screws on the heatsink and 3 on the heatsink fan. Take all 7 out and unplug the fan from the mobo. The fan and attached heatsink should come off pretty easily. There is a small release screw on the top of the pink cpu mount. Just turn it counter-clockwise 180 degrees(1/2 turn) and it will release the CPU. To remove the CPU gently lift from the bottom(opposite the release screw) and it will come up. To install the new one just reverse the directions. Note: to line up the CPU properly you will notice one corner of the original CPU is different from the rest. Usually a missing pin(s) in that corner. You will want to line up your new CPU exactly the same, set the top edge on its edge next to the release screw and lower it into place the same way you removed the old one, then turn the screw 180 degrees clockwise. Good luck with your adventure. This video should help you with applying the thermal paste between the CPU and heatsink) as this is VERY important... http://www.youtube.com/watch?v=o7rPqCvCt0g and here's the link for the pics for computer disassembly. They are from my disassembly of my IQ526 but should be pretty much the same because they have the same motherboard.
http://s93.photobucket.com/albums/l61/jbranyon/HP%20IQ526%20CPU%20upgrade/