Run your hand down the oil dipstick tube until you reach the
bottom at the crankcase. Feel forward (towards the front of the engine)
approx 2". You will feel the single mounting bolt, the sensor, and then
the cable.
The cable then runs behind the power steering pump and up over
the camshaft cover as 'Tab' said.
Although Haynes says to remove the nearside engine mount and
do it from underneath. You can do it from the top. Undo the single
mounting bolt on the dipstick tube and try pulling out the tube.
It should be a push fit. This will enable you access the mounting bolt,
and access will be better still if you remove the heatshield from
the exhaust manifold.
Don't forget to blank off the dipstick tube hole if you remove it.
You don't want to go dropping your bolt down into the crankcase.
It's quite fiddly working blind down there.

Stick a dumpy screwdriver, or something similar, in it.
The sensor mounting bolt uses the same size socket as the heatshield
bolts. This will save you fiddling around trying to find the right size
whilst working blind.
Be prepared to learn a few more cusses and swear words when
you're buried in the engine with your legs waving in the air.
