When you say train I assume you mean trim or prune. Neither need pruning unless they have become too big and you want to reduce the size. Yes both can have a trim if you want to. With the red robin they say the time to prune is after flowering but I have a hedge of it about 20 feet long and 5 feet high and i give it a light trim a few times each year to keep it in shape and this seems to stimulate new red shoots throughout the year. It's not what the text books say but it works for me.

Neither of these shrubs needs any training as such. As for pruning, Inverglen's advice above covers it.

I have just trimmed back one of my 3 Choisyas to just beyond where the flower stems are attached to keep it in line with the pathway. Early flower shrubs usually have a splurge after blooming so need keeping where you want them, not let too tall, or knocking you off the pathway. Think what the contractors do to corporate plantings when they descend on your local supermarket car park. A bit of a shave or short back and sides!