in my case it turned out it was the turbo oil seals were gone, effectively dumping oil into the exhaust.

as for removal I had to
- remove battery and battery tray
- remove intake pipes (airfilter box, air flow meter etc)
- remove bracket holding the exhaust back pressure sensor)
- undo exhaust clamps from turbo outlet, dpf to egr cooler, and clamp from dpf to exhaust
- there's two bolt at the bottom drivers side of dpf to be removed
- two bolts (12 spline socket head (10mm i think) that hold the DPF to the block
- one bolt holding cat converter end of dpf to head
- remove egr cooler, disconnecting water hoses and small right angle bracket to block, electrical connector and hose to turbo inlet
- I removed temperature sensors in dpf so they wouldn't get caught
then supporting the engine and transmission on jacks I undid the engine mount, gearbox mount and dogbone mount.
slowly lowered the jacks and pulled the engine as far forward as I could I was able to get the DPF out through the top, the main obstacle is the mount that holds the DPF, if necessary you may find it easier to get that out, the DPF does lift out over the turbo if you can get it past the DPF mount bracket.
I don't know if the AWD setup will allow much movement of the engine and gearbox.

but basically I just removed anything connected to the DPF and dropped the engine down and forwards to get it out.