I have a case feeder for my 650, but I was thinking about it and bullet feeders.
The expensive part of both of them is the hopper with the rotating plate to align and drop the case/bullet into the feed tube.
The mechanics at the shell plate end would not be that expensive.
If you were to route the shell feed tube to the left side of the press, maybe a foot above the mount, you might be able to get a series of small bends in the case feed tube so that you could manually drop cases into the tube with your left hand.
Same with the bullet feed tube except it is already on the left side, so it would be a straight drop.
A belled mouth at the top of each tube would allow you to drop bullets/cases in with out much precision.
The tubes could hold 10 or so bullet/cases depending on length of the item.
While feeding bullets/cases into the tube mouths would be manual, it would not be such a precision operation as placing them correctly on the shell plate.
Also, since the tubes hold a quantity of the items, timing would not be important. You could add them while the piston was moving up or down which would not require stopping of the process for manual insertion.
Maybe without the support and hopper for the bullet feeder there would be room to reach around behind the press to manual feed cases into a straight drop tube.
You should be able to buy just the lower mechanics for the case feeder system from Dillon, and probably for a bullet feeder also.
Thoughts?