Yep, have done two hogs worth at a time many times. Have also butchered our own, although we hire it done now, and it's worth every penny. But we have a reliable small local slaughterhouse we trust.
If at all possible- and that means if you have the proper power grinders- grind all the fat first. This makes even rendering a LOT easier, believe me. You still get "cracklings" although they are in small bits, not large chunks.
If you can't grind it first, just cut it up in small chunks (as small as practical, don't get paranoid about it) and put it in either large- ALL stainless steel- kettles, or roasting pans. Put in the oven at 300 degrees and forget it.
Well, you won't be able to forget it- the entire house will smell like roasting pork fairly quickly! But you don't have to worry about scorching it this way, or stirring it, or much of anything until it gets close to being done.
You'll know you're getting towards that point when the remaining pieces are brown, and a thermometer in the liquid part is getting well above 240 degrees. You want 255 for lard that will keep for awhile.
When it reaches 255, CAREFULLY remove it from the oven. If there is ANY chance of a spill, turn the oven off, open the door, and let everything cool down for awhile. Lard that hot is VERY dangerous... a burn is not the way to make your day!
Once you can handle it, pour it first into a stainless colander or other strainer type object. Don't worry about the tiny bits at this point- I always strain it twice, and it's a LOT easier than trying to get it through cheesecloth first while holding that heavy roaster pan full of cracklings and other bits.
Strain it a second time through cheesecloth, or some other coarse meshed cloth. Don't try to get every single tiny bit through the cloth if you want the clearest, finest grain lard. Once you've gotten most of it through the cloth, carefully remove the strainer with the cloth full of tiny bits and what lard didn't go through, and squeeze it over another, separate container. This is the container I also press the cracklings into- by wrapping them in a couple layers of cheesecloth and twisting the top to squeeze every last bit of fat possible out of them.
This second container is fine- but it's not perfectly "pure" and won't keep as long as the clear lard. It also may have a bit more "pork roast" taste. I used to use it in dumplings and biscuits and for frying, where the flavor didn't hurt anything.
If you are REALLY picky, you can let the "pure" lard cool and settle, and then scoop most of it off the top, leaving any darker fat on the bottom, and put the two types in separate containers. This is probably only necessary if you're planning on using lard for everything, including delicate flavored stuff like cakes and cookies.
Fill your containers as close to the top as possible- you want as little air to access the lard as possible. Once it cools a bit, I usually put a doubled piece of saran wrap on the top surface to help exclude air. Oxygen is what helps it go rancid.
You CAN add vitamin E to help it keep longer- if you don't have a way to freeze it, I'd highly recommend it. Not sure how much- I used to open 10 or 12 capsules and add them to a 6# Crisco can full of warm lard, stirring it in well. But I generally freeze my finished lard now.
I've also read that if you add 6# of Crisco or other hydrogenated vegetable shortening to every 50 # of lard it will help it keep quite a bit longer. Since our whole purpose to using lard and butter was to avoid those hydrogenated fats, I never tried that. But if it's a choice between losing quite a bit of the lard when it goes rancid quickly, or saving more of it, it might be worth experimenting with.
Hope this helps
Summerthyme