I've seen a post on that before - maybe even here on Marlin Owners - not sure.
Often, I load with a little "arbor press" which is much like a small drill press, without the drill. However I freely admit to using very nice Wilson dies for that loading.
The Wilson dies I use are similar in appearance and function to the little Lee Loader die kits many of us used with just a hammer or mallet to load. They're just a lot nicer and have interchangeable bushings to allow for varying the neck tension to suit.
I don't know where that old post on the guy loading with home-made tools is - but it was pretty cool. Loading can really be reduced to the basics very nicely.