I'm no pro but these worked for my dog, keep in mind that my dog is way smarter than your dog Haha ok seriously. Play fetch with an antler to start him/her off use a phrase like "find the horn", "fetch it up", etc every time they go and get it so that they associate the phrase with finding a horn. Then "hide" an antler in your yard and use the phrase, reward them with a treat every time they find it to reinforce what you are wanting. Then go shed hunting. Take a bag of treats and go out, don't say the phrase yet, when you find a shed, don't pick it up, but call your dog over and use the phrase (it will probably be a little more difficult for him/her to find it because your scent will not be on it) but reward them for even sniffing the horn and if they pick it up (you can help them with this) give them a treat. Do this every time you find a shed. As they get better, you may see a shed near them, use the horn phrase and they may be able to find it even if you are far away and eventually, they will bring you a horn on their own. Of course reward like crazy (treats, praise) for this. That's what I did with my dog, and it worked pretty well. Good luck!
antlerdogs.com, antlerlabradors.com, or you can punch up Dokkens dog training and go to thier website to learn more info. Or you can call me, Drew Edwards at 775-397-6299. I'm not a pro but I can tell you what I know. fatrooster.