This is a quick summary of the steps to change a lower suspension member on the LR3/LR4 (Discovery 3/4 in some markets), originally posted on NCLR site.  Please familiarize yourself with the process using the workshop manual, as this is only an overview.

Graeme's DIY guide to changing lower suspension arms (aka lower wishbone, lower control arm).

1.  Thoroughly power-wash the entire suspension and wheel-arch area two days before and drive the vehicle to ensure you haven't drowned anything (electrical) before you start.  Allow to dry.  You'll be glad you did when working underneath as getting mud and dust in your eyes isn't fun.

2.  Caution: when doing any of this ensure you wear eye protection and have the vehicle securely blocked, and use stands not just jacks (that can and do fail).

3.  If possible, get underneath the day before and precisely squirt a good penetrating oil ("Liquid Wrench", "WD 40", "Plus Gas", whatever you use, personally I use 50/50 mix of kerosine and ATF) on all the bolts and nuts.  Avoid getting it on the brakes!

4.  Check to make sure the replacements you have look like the original before starting .... sounds obvious but it is not unusual to get incorrect parts.

5.  With the road wheel still on the ground, slacken the hub nut (with most wheels this is possible, some you may need to take the wheel off first).  You'll need a 32mm thin-walled socket (RoverWare has them if you need one LRT54002).  This might be the hardest part of the job as it is it is torqued to 258lbft so will take at least that to remove.  You'll need a big bar .... or at least a big fridge for the beverages.

6.  Now, here's the bit that nobody tells you.  Mark the inner bolts and washers (they are an eccentric cam) with a Sharpie or paint marker to ensure you put them back int he same place.  This will mean that you are almost dialed back in and can drive safely for a while without an alignment (which you will need anyway, but you'll be close doing it this way).

7.  Clean all the threads of the bolts.  Harbor Freight (no affiliation) do a really cheap kit of small wire brushes that is great for this.

7.5  Place vehicle in "access mode" or whatever they call it, and measure from hub center to wheel arch.  Write down this number.

8.  Slacken the lower ball joint nut and remove the lower damper using a 24mm socket (and big breaker bar).  Make sure you have a big hammer ... don't use it, but "threatening" to use it usually works!

9.  Undo the suspension arm nuts, and start praying that the bolts aren't rusted solid into the bushes.  Normally they are good here in California, but where they spray salt on the roads they can be corroded to the point where you need a Sawsall.  Might be worth planning to replace them anyway unless you have a spare vehicle so that you can wait while replacement arrive.

10.  Remove the caliper and disk.  You'll need a puller for this.

11.  Split the lower ball joint from the hub carrier (aka upright).  Crow bar and hammer is the usual way.  Put tension on with the crowbar and sharp blow with a 2lb hammer.  The correct way is to use a cantilever ball joint splitter, but a "pickle fork" will also work (but that is a butcher's tool!).

12.  Go for beverage break; see 5 above.

13.  Get that crowbar out again to gently lever out the wishbone from the chassis.

14.  Pull the hub off the driveshaft enough to get the ball joint out.  It helps if you have two people and six hands for this.  If you don't, go to 12.

15.  You're free!  You should now have the old wishbone free.  If you're not swapping it, just changing the bushes, then you'll need a press, lots of penetrating oil, various sockets or drivers, and a lot of patience.  I'd just change out the wishbone, as they are only about $150 I think, and the bushes are half that.

16.  So lift your new wishbone (or re-bushed wishbone) into place.  Fit the ball joint, and add the nut finger tight.  Using the pre-marked bolts (or transfer the markings on to the new bolts), attach to the chassis, greasing the bolts first (lithium is best IMNSHO).

17.  Remember, don't tighten anything up fully; leave the ball joint and the mounting bolts loose.

18.  Put the hub nut back on and pinch, but don't fully tighten.

19.  Tighten ball joint (you might need to jack under the wishbone to do this) to spec.

20  Fit wheel and tighten hub nut to spec. (258lbft)

21.  Tighten the main mounting bolts to spec., ensuring the marks you previously made line up.

22.  Measure the hub to wheel arch distance and note that it should be the same as it was.  If it isn't you may need to recalibrate the suspension height, and I know nothing about that ....

23  Go to item 12.

24.  Have someone test drive the vehicle, or do it yourself the next day (due to item 12).