Replacing the top two bulbs is easy - straight swap, but it's a pain in the arse getting the clocks out of the dash. There is a screw you might miss if you don't know about it under a black triangular bit of trim on the left of the silver surround (with the fan grilles, clock, etc). There's a plastic clip at the bottom of the silver surround you'll probably break when removing it. You'll need to at least remove the indicator stalks to get the clocks out, if not the whole steering wheel if you can't manipulate it out through the gap.
There is a bit of green cellophane at the top of the clocks you'll need to cut out a bit of plastic in order to get at to remove, and there's also a bit of green cellophane on the trip/mileage counter if you've got a digital dash - this is tricky to remove and it's very easy to break the LCD panel.