My personal preference for force feeding BHP hatchies is to use pinky rats, I've never had a problem getting them down.
Usually after 2-3 force feeds you can get them assist feeding.
Once they are assist feeding try leaving a pinky rat in with them, after they have taken the assist fed item down they may eat it by themselves, once they start doing this it will only take a couple more assist feeds till they are feeding without assistance then there is no looking back, they turn into little pigs.
Before force feeding it is always good to try other things. I have used day old quail and day old chick heads in the past with great success, or scenting with either of these items has worked at times also.
I think in your case though force feeding may be the best option as the little guy didn't absorb its yolk so would be needing some nutrients asap before it loses to much condition.
Buffcoat - Generally I find BHP hatchies are frightened of live food, it may work on occasion but more often than not it doesn't work. Works fine with allot of other species but the BHP's really seem to stress .