If you have a bunch of bacon fat on hand and want to use it for lubing your patches, you can do it but it will have to be cleaned up first to get rid of the salt and bits of other "stuff" in it. It would way easier to just buy a pound of pure lard at the store. It's the same thing as bacon fat minus the salt and "stuff".
Here is how to clean bacon fat so that it is usable as patch lube. First, you melt the bacon fat and pour it through several layers of cheese cloth. This filters out the solid bits and gets the grease ready for the next step. Take the filtered grease and put it in a pan of water. You need about three times as much water as grease and the pan should be small enough in diameter that the grease is thick on top of the water. Bring the water to a gentle boil and let the water/grease mixture simmer for a few minutes with occasional gentle stirring. Remove the water/grease mixture from the heat and let it cool completely. If you are doing this in the winter, just put it outside until it is cold. When the grease is hard, remove the block of grease from the top of the water and examine the bottom of the chunk for any trash. If you see any, scrape it off. Put the chunk of grease into a pan of fresh water and repeat. Do this at least three times to get the grease nice and clean and salt-free. you will now have a nice piece of clean lard.....just like you could have bought at the store in the first place.
You can use bacon grease as a patch lube if you are willing to clean it but you have to ask yourself if it is worth it when lard is readily available at the store and it is cheap.