Fairly simple. Remove the air filter and the breather hose attached to it (Held down by a few screws).
The MAF sensor is connected to the breather hose on either side of it (Engine side and filter side) by 2 rather annoying clips. Remove these, then the sensor should just pull out (Maybe with a wiggle). Its the whole centre piece, and you should remve the connector from the top of the sensor, to prevent damaging it.
Replacing is basically a reverse of that, but those 2 annoying clips I found to be extremely fiddly.