OK, I did mine on an x3.0 2003 x5
easy to take apart everything,
dont save any old hoses just cut them.
First read all forums on topic:
to re install properly : this is in addition to all those forums and is for X5 3.0 2003
The new oil separator,put it in place, then take it back out 1 inch , loose at angle.
1. the first hose:from valve cover (near vanos) to bottom of oil separator , fairly easy to install, just be gentle, from the valve cover it will route under the intake manifold.
2. Hose 2 - from side of oil separator to left side of top of manifold - be prepared for hell. Unless you follow these instruction.
The secret - sorry no pics, starting form the top of the manifold feed the hose through the intake manifold and while going through the intake manifold there is a cavern that will direct the hose straight to the oil separator (there are 2 caverns the other one wont work)
then the hose comes out to 1/2 of the oil separator side intake , the side intake points towards the radiator.
This is where its very hard, because its almost physically impossible to push the hose into the oil separator because your hands cant seem to fit there, so
take 2 thick flathead screwdrivers, one will catch the back of the oil seporator kind of like a leverage to press the seporator towards your left (to radiator) it will basically push it towards the radiator, next the other flathead will catch the ring of the hose and push it the opposite direction, sort of like these 2 flat heads are like a clamp,
once the hose goes into the separator hole then there is about 1/4 to /12 inch of room to turn the snap ring of the hose shut.
if you gone this far then no need to further explain after that its all easy.