I have recently just done this myself. I damaged the cable in the process, so ordered a new one & everything is fine. Here are some tips that might help you out:
When you get to the mainboard, you will see that there is a total of 4 cables that need to be disconnected. Take a photo of each cable BEFORE YOU DISCONNECT. This is so that you can refer to it when re-inserting the cables. You will be able to see how far in the cable actually goes.
The two big cables have a clip that pulls up to release them. The two smaller cables have a clip that needs to be loosened (pryed out) with a small screwdriver (or similar) - be very careful when doing this because they will break easily.
Make sure you have the buttons in the right way before re-assembly. Check that they aren't tight. If they are - do a little filing to get it right. If they are tight you will hate yourself when you finally have it all back together.
Remember to take the clear (led indicator) plastic piece from the old case & put in the new one.
When you put the connector cable in it must have a loop in it - You should be able to copy this from the old cable. Be careful when putting the top cable cover on that you don't damage the cable in the process.
That is all I can think of now. Good luck !
Edit: When you are putting the hinge together, make sure both pieces (top & bottom) are aligned properly. When I was doing it I forgot about this & pushed the hinge through the first part fine, but because the second part wasn't aligned when I pushed it through it cracked it, rendering the case completely useless.