Hi al,
My bimmer failed its MOT because of the o/s lower ball joint...
Getting it out is relatively easy in comparison to getting it back in!
Sorry to be the bringer of bad news but you can only get a new one back in with a press...I only had the use of a ratchet style manual one and it was a biyatch to say the least...

ghead
I removed the control arm (recommended and should only take 15 minutes) - pressed out the old joint and then pressed in the new one using a little lube. It took about a half hour to get the joint lined up nice and straight before it would go home...very fiddly and I could have done with an extra pair of hands to help speed this up!
You will need a special "bit" that fits around the ball joint so that when you press it it doesnt ruin the surrounding rubber...fortunately my mechanic loaned me one...I'm not even sure what the name of it is but you wont be able to do the job without it.
Hope this helps,
J...