You could opperate an AHS or AxemanAnderson boiler like a hand feed. You would use the standard 'funnel hopper' with the AHS, but with an AA boiler, you would have to remove the access cover on the tranfer head of the auger, and make a sort of funnel so you could shovel coal down the feed tube.
With the Axeman Anderson,, you could manually 'shake' the unit with the ashing handle.. With the AHS, which uses an electric motor to run the shaking mechanism, you would have to rig up a crank handle to replace the motor to manually shake the ashes..
Both the AHS and AA will burn Buckwheat, or pea, using the stoker mechanism.. Both will also burn Nut,[if hand fed] but the amount of heat created, and air needed through the firebox and heat exchanger are unknown to me.. I have burnt some leftover nut coal in my AA260, nothing seemed different from burning Pea coal.
With either the AA or the AHS, to create rated BTU output, the combustion fan still needs to run, and a circulator pump needs to run, so you are not independant from electricity. If the boilers were plumbed just right, and the chimney had a strong draft, you could get maybe 25-40% rated BTU's by allowing gravity flow for the water, and propping the inspection door closed to make the chimney draft pull through the coal bed, instead of over the top of the bed.. You would have some heat, but not rated.