Generally you do the full training program. Only difference is a few items would not need to be checked on the ride since you already have the type. And the training will be very easy, BTDT.

There is a rarely used FAR provision to allow for a short course for people coming from another airline on the same equipment. But I've only seen airlines bother with that when they knew they were hiring a large number of such folks in a short time-frame. I think the course may have to be customized based on where the pilots are coming from, so not something they would do for a few stray cats here and there. I know one or two regionals did it when flying was getting moved around and lots of people were chasing the flying.