No split pins involved.
You don't need to remove the axle, but there is no room to get a socket on the balljoint nut so you'll have to use a big spanner.
Unfortunately I can't remember the exact size. I think mine was 22mm but it could be 21mm or even 19mm.
Once the balljoint nut is off you will need smack the side of the hub with a hammer to free up the bolt and then pry downwards using a long crowbar/prybar to get the ball joint out.
Watch this video for help regarding actual control arm replacement: