Whatever you use, bread, grease, wet paper towels, etc., the concept is all the same. You are using hydraulic pressure to jack the bushing out. That also means that whatever you are using for a plunger has to be a tight fit in the bushing hole. Also, when you smack the plunger, you need to drive it in straight. If you hit it off angle, then that binds it up in the bushing bore and that kills a lot of the force you are trying to tranfer to your "liquid".
The only nut part that works well is the one in the big hole. If you try to drill and tap the two sides and jack it out, than you will break the screws off since the holes will not be through holes unless you drill into the crank. You can however, drill and tap the two sides for 1/4" or so and bolt a nut in place using a washer over it and use that to jack it out. I've done it that way but it takes too long for me.
All other things being equal, welding a nut to the bushing is easiest.
