for the older one, i would just take him on a set schedule, without using any potty related language. use 'come with me' and such, and take him to the bathroom every 1.5 to two hours, first time as soon as he wakes up. there will be misses for a bit, but his body will adjust to going on a schedule, and then he'll start to let you know.
we sing a song as a distraction, but you could also read a book or tell a story or just have a conversation.
for the younger one, pretty much the same deal, except that s/he will need to go more frequently, and when you discern a signal, then you could go on the signal.
we use diapers for back up, which just helps us out, and now we pretty much use one trainer per day (changing it every 24 hrs if it didn't get wet/soiled), and are looking to move to undies in a few months (summer here).