Here's the underside of mine
As hungrymonkey said, to not compromise the glue on the rubber pads by removing them I prodded with my philips head jeweler's screwdriver until i found a soft spot then rammed it through and undid the screw.
The holes with rubber plugs I simply removed the plugs with a pin then discarded them.
you'll need to remove all the keycaps to disassemble the unit
Once you have all the bottom screws off, remove the lower plate and undo the screws on the side 'arm' thing
Then you can begin prying apart the main part of the machine, there are more screws, but they arent hidden, pay attention to how the rail thing and the pin works, there's an odd inbetween piece you need to make note of.
you can safely remove the big circuit board by disconnecting the ribbon cable, its got a nice plug and socket and can be removed without damaging it.
To replace the LEDs just pick up standard 3mm LEDs, just make sure they are wired with the 'spades' inside the LED pointing the same direction as the stock ones.