I can't speak for boiler but an ISO kit with legends seems pretty doable to me. I'm not sure about custom legends for the ISO Enter though -- I think I remember hearing that SP doesn't do them... ?
Thanks for your reply. Sounds promising!
Concerning thge ISO legends:
The Klaxon set had one as shown in the above picture. Of course this isn't the Cherry type, but at least it's better than a naked key among a bunge of keys with legends