I don't bother with the plastic or rawhide mallet, but I use either a brass or a nylon punch between a small steel hammer and the sights.
The real trick to simplifying the job is supporting the barrel solidly. For that, you might consider drilling a hole that's roughly the barrel diameter through a block of wood and then sawing the block through the center of the drilled hole. Use the two pieces in a bench vise with the barrel clamped between them. You need to make sure to choose a block of wood that is not going to split easily.
The real trick to simplifying the job is supporting the barrel solidly. For that, you might consider drilling a hole that's roughly the barrel diameter through a block of wood and then sawing the block through the center of the drilled hole. Use the two pieces in a bench vise with the barrel clamped between them. You need to make sure to choose a block of wood that is not going to split easily.