You don't need a manual to swap solid arb's for the ACE system, it is all nuts and bolts apart from telling the BCU that the ACE system is no longer fitted.
Got one on the driveway now, V8 Disco 2 having the change done.
Depending on the engine, you'll need a different aux belt or a different belt AND an idler pulley to replace the ACE pump. V8's normally just need the different belt.
You need:
Drive belt and pulley if TD5, V8 just needs the different belt.
Solid ARB's front and rear
New ARB rubbers
New drop links
Single reservoir for power steering (not essential but looks right)
You'll probably need to cut the old drop links off as the threads are normally rusted solid.
Drain the fluid out of the system as much as possible and catch what's left when you undo the pipes.
More or less strip off the old and fit the new. You'll need a good set of axle stands, tools etc.
RAVE doesn't tell you how to do the job, but worth getting anyway.
Peter