Feeding Recycler by hand is one of most annoying things in IC2.
So, simple solution - when you put stuff in Recycler it is consumed immediately, like geothermal eats lava cells, getting one "charge" per item, up to 512. Then recycler works with charges as it does with items in input slot now - 1/8 chance per charge to get scrap, 2.25 sec and 45 EU per operation, etc.