At present, it seems to me that the only way for something to support the stuff is if it uses a vanilla material in its Anvil-Repair recipe. It might be a bit of work for you, but it'd be neat if we could add this functionality to things like Railcraft's Steel Amor, or (amusingly) Witchery's Witch Hunter Armor.
For that matter, it'd be nice if we could add it to stuff that doesn't use "materials" in an anvil, like Bows.

+1