Shouldn't be too difficult. Take off the aly shield over the manifold
and you should be able to see the front one. The back one is at the
bottom of the down-pipe, should be visible from under the car. Torque
is 55Nm for both but you'll need to guess that with an open-ended
spanner. They both plug in under the throttle-body cover. The back one
has a bit of a tortuous cable-route so tie a bit of string to the
connector before pulling it out so you can use the string to pull in
the new cable.

Cheers,

Colin.