Modification on my prevous method (I kept getting more honey on me than in the feed)
Mix bute with small handful of usual feed, offer to hungry horse, horse can't resist trying at least a couple of mouthfuls before looking at you in utter disgust and leaving the rest. Mix rest of feed in with left over horrid stuff. Horse is now used to awful taste and doesn't notice the now very diluted taste.
I've had this problem quite a lot recently in that my horse just refuses to eat his supper with bute in. I followed someone's advice about syringing it in and he totally wasn't expecting that!! He was fairly cross about it afterwards but I think that's because I surprised him and he thought he was being wormed which he doesn't mind!!
So used a large syringe and mixed a bit of warm water with the bute and shook it around and put it straight in and held his mouth closed.
Mine have never refused a treacle sandwich. Two rounds of bread one side heavily pasted with black treacle sprinkle bute over that, then sprinkle with a bit of sugar over the top of all that. Top layer of bread.
Hmm, not sure about syringing it down, especially if just mixed with water. Apperently it can cause ulcers in the mouth, especially if a solution of it is swilling around the mouth, while the horse looks for a way to spit it out!