Alternate feedings...morning feeding--bottle of electrolytes, 2 hours later a bottle of milk replacer. Middle of the afternoon--bottle of electrolytes, 2 hours later bottle of milk replacer. What's even better, if you can, break the feedings down to every few hours like a half bottle of replacer...wait a couple of hours, then the electrolytes...wait of couple of hours, then another half bottle of replacer, and so on. The trick is to keep him hydrated with the electrolytes and nourished with the milk replacer. If the calf continues to eat, you've got half the battle won.
Try some spectam (red pig scours medicine)...20ccs first dose, 20ccs there after. Do this twice a day. Also, squirt probios, or some type of microbial, into the calf's mouth at each feeding. Don't discontinue the milk for more than 2 feedings in a row...when a calf gets weak from lack of nutrition, it's harder for it to recover. And, electrolytes do not contain nutrition.
Watch the calf close for respiratory/pneumonia type problems.
Also, put some dry calf starter/calf manna feed out and keep the water clean and fresh, and try to keep the calf's pen as clean as you can.
And remember...it's not the scours that kill the calf. It's the dehydration from the scours that does.
Alice