If you’re using the sliding rod style like this…
I suggest take the bucket off first. Remove the keeper bolts (the little cross bolts that keep the pins from sliding out). Mark the cross bolt end of the new pin with a sharpie or something similar to locate the rotational position of the cross bolt holes to assist with finding the cross bolt hole. Push/tap the old pins out with the new pins. Coating the new pin with grease may assist with sliding the new pin in. Having a nail or something similar to use as a drift to line up the cross bolt hole can be useful.
Once the pins are in and rod installed in the tube, put the bucket back on. With tractor and bucket on a level surface, set the bucket level on the ground. Set the rod for level.
If you use forks, grapple, or other stuff on your loader, most likely you’ll find level at ground is somewhere other than it is for the bucket. Not sure why level for a grapple would matter, but level at ground for forks is kind of nice to know. Might consider making a mark of some sort on the indicator rod to show level for forks.
That’s what I did and it was pretty easy. I didn’t even need a hammer to tap the pins in/out.