This is a very easy replacement.  Once you have the new ones in your sight it will be easy to see all that is necessary to remove for replacement.  The most important thing about this job is use of the proper tools.  You need a proper size line wrench ( available at Sears or Auto store) for the hydraulic line and the right good quality wrench or socket for the mounting bolts.  You should spray all bolts and and most important the hydraulic line hours before doing the job a couple or more times with a good quality liquid wrench.  When removing the accumulator and especially the line be sure to have the tool on right and square even when applying pressure.  You do not want to round off any fitting or bolts.  That would make an easy job hard.

You should first start to loosen one of the lines.  Just begin to loosen one line until it starts to leak.  The system is under pressure so let it leak until the pressure is gone.  The leak will stop when this is so.  Now the pressure in the whole system is released.  It is now just a simple matter of removing the lines and mounting bolts and replacing the units. 

Now top off the hydraulic fluid reservoir and start the car.  The system will bleed out itself.  On some early 6.9 and possibly other euro early models there may be a bleed valve at the rear level control valve.  In most cases this is not necessary to do but if the car does not drop to the proper level you may need to  bleed at the valve.

They are located in different places on different models.  Most of the time the rears are above the differential under the car.  The fronts are close to the struts.  On some models the front may have a fifth one at the left inner wheel well.  In all cases you can locate them by following the hydraulic lines from the strut.  It always goes to one.  They are more than one line but one goes to the accumulator.  Hope this helps

Thanks

Rudy