Hi Deansmig andwelcome to the forum. Your post reminded me of an earlier time this had come up, on this thread http://poultrykeeperforum.com/viewtopic.php?f=3&t=5771&p=32228&hilit=Puppy#p32228 which you may find interesting. As the owner of a Norflok, I would say that your terriers will need careful training as of course they will find the new pullets very interesting and will initially regard them as prey, especially as they are young birds, in anew place, and thus probably more flighty than they will be once they have settled down and started laying. I would myself keep them in their run for a couple of weeks, until you can be sure of catching them in there and picking them up, as otherwise you will have to chase them round the garden to catch them, which will panic them, and set back their training programme. Once they are a bit tamer, you can let them out, initially without the dogs being around, as the pullets will need to explore the new area they have access to, before they can feel safe and calm in it.
Whilst they are in the run, you could take the dogs to the outside, on leads, and do the usual Sit and Stay and Leave training, with rewards, when they are calm and quiet with the birds. Once they get used to the sight of these interesting strangers they won't find them so interesting, but when you eventually get to the stage of letting the girls out to the garden, you will need to keep the dogs on leads for quite a while and supervise them, until you are sure they won't chase the pullets. Even if they are sensible with the birds when they are just walking around, if one of them is startled and flies away squawking, it would be too much for any self-respecting Westie to ignore and he will give chase.
Of course with any luck, one of the hens will peck the dog hard on the nose, which happened to my Norfolk when he chased a hen- instant cure, never shows any interest in any of them since then!
By the way, Dinosaw, if you're reading this, how is Tuppence getting on, a year later?