I did mine by drawing the oil out through the filler plug with a syringe.
But there's a strainer over the pump only accessible by stripping the unit out, I don’t know how competent you are with DIY maintenance but done slowly this is not nearly so scary as it looks.
I took off the prop shaft centre bearing bracket, then take out the prop shaft bolts at the diff ( very tight) tie the shat up to avoid any problems, then give the diff a good clean with a soft wire brush to avoid getting muck inside, take out the Haldex unit making sure you have something to catch the last of the oil, give it a clean out and put it back. Dont get any contamination in there ad if you decide to wash the internals with anything be sure its blown clen before re fitting.
Be sure to follow the re fill instructions its very important and not so complex once you do it, it is necessary to fill it to the level of the filler plug then to run the engine ( I did a short run in mine and engaged decent mode) then you have to re fill to the level and extract some of the oil using a syringe, read the thread which I linked above it jumps around a bit but all the info is there.