Removing and refitting the turbo itself is not a difficult task, but the mass of other parts that need removing to access it makes this a reasonable amount of effort.
You will first need to remove:
Engine covers. [5mm Allen]
Air inlet ducting and air-filter. [5mm Allen]
Inlet manifold. [10mm + 11mm Hex]
Injector pipes. [17mm open-end wrench]
Injectors. [8mm Hex]
Rocker cover. [10mm deep-Hex]
Turbo to intercooler pipe. [10mm Hex + T30-Torx]
Airbox to turbo pipe. [5mm Allen]
EGR to exh.-manifold pipe. [T45-Torx + 7mm Hex]
Exhaust-manifold. [10mm deep-Hex + 12mm deep-Double-Hex]
Front engine-undertray. [8mm Hex]
Engine reinforcement-plate. [16mm Hex]
Exhaust vibration-damping rods. [13mm Hex]
Step 1: Unbolt Exhaust:
Remove the two nuts holding the down-pipe/cat to the back of the turbo using a 17mm wrench and work the down-pipe back off the studs.
Step 2: Remove Oil-feed:
Remove the banjo-bolt that attaches the turbo oil-feed to the block using a 14mm wrench, remove that end of the oil-feed pipe and loosely screw the banjo-bolt back in a few turns to stop any oil leaking from the block. Put some cloth against the block under the pipe to catch any drips and remove and retain the 2 copper washer-seals as they are easily misplaced.
Step 3: Remove Oil-return Pipe:
Reach under the turbo, locate where the lower oil-return pipe enters the rubber-hose to the sump and loosen off the upper jubilee-clip using a 6mm-Hex socket or flat screwdriver if you can get access. Let the jubilee-clip slide down the rubber hose.
Step 4: Unhook Waste-gate Vacuum Line:
Slide off the rubber-hose that runs to the waste-gate on the turbo.
Step 5: Lift Turbo Out:
Make sure the turbo's weight is supported, remove the two bolts holding the turbo-bracket to the block using a 13mm wrench and lift the turbo out, carefully sliding the lower oil-return pipe out of the rubber-hose.
Step 6: Fit New Turbo:
**Ensure all oil-feed pipes etc. are swapped over to the new turbo**. Lower the new turbo into position, sliding the lower oil-return pipe back into the rubber-hose and loosely refit the two bolts.
Step 7: Refit Oil Feed + Return:
Tighten the jubilee-clip on the oil-return hose and refit the oil-feed hose back on to the banjo-bolt, making sure the copper-washers are in place either side.
Step 8: Refit Exhaust Vibration Dampers:
Place the exhaust vibration-damping rods back in place to locate the down-pipe and loosely refit the 13mm nuts.
Step 9: Bolt Exhaust Back On:
Refit the neck of the down-pipe to the back of the turbo and tighten the 17mm nuts.
Step 10: Refit Exhaust Manifold:
Place the exhaust-manifold over the studs on the cylinder-head and manoeuvre the turbo into a position where the bolts holding it to the manifold can be fitted. It can be trick to do while keeping the gasket aligned. Turn the three manifold-to-turbo bolts using a 12mm deep-Double-Hex (12-sided) socket until the manifold is seated, but do not fully tighten them.
Step 11: Tighten Up Turbo:
Lift the turbo to take the weight off the manifold and fully tighten the two bolts holding it to the block using a 13mm wrench. They are a pain to get to but it is doable, also a lot easier with someone else lifting the turbo.
Step 12: Tighten Manifold to Head:
Replace the twelve copper-nuts that hold the exhaust-manifold to the cyl.-head and tighten them using a 10mm deep 6-sided socket, as they strip easily with 12-sided ones.
Step 13: Tighten Manifold to Turbo:
Tighten the three bolts holding the manifold to the turbo using a 12mm double-hex [12-sided] socket.
Step 14: Hook Waste-gate Back Up:
Re-connect the rubber vacuum-hose to the waste-gate.