The Circuit Writer Pen is the exact one I used.
Positioning the chip is a bit tricky. Depending how the pins broke, will determine how easy/hard it is to get it back in the exact position. Take your time.
I used the point of a scalpel blade to hold it in place while applying the glue.
You could try something like blue tack on one side, while you glue the other, then once its set you could glue the opposite side.
Applying the silver will complete the circuit, but it is tricky, I did it once (as mentioned above) then ended up wiping it all off and starting again. It is best to do it in stages. I used the point of a needle/pin to apply it the 2nd time. You want to avoid bridging the pins.
I highly recommend a magnifying glass and lots of light.
To be honest, I think I may end up trying to solder it. The idea seemed pretty scary to me, but after watching this video it doesn't seem too hard:
If you're not confident doing that, maybe just call your local electronics repair shop, or a mate who has some experience soldering. That way if they stuff it up (and are insured) it won't be you having to fork out the money to buy a new logic board.
Once you think you have it connected, turn on the computer and download smcFanControl. It's a menubar item that will show you the speed of the two fans. Hopefully you'll see in the menubar the rpm for both fans.
I kept getting a reading of 0rpm for the broken one, which meant one of the pins wasn't connected properly or was bridged.
The fans should be spinning around 2000rpm. If there is not speed reading from the fan, it'll be spinning at max speed (around 6000rpm).
Don't forget, be patient, and don't rush. If you're getting frustrated go make a cup of tea. :P