I am sorry that your question hasn't been picked up yet, so here I go -
Why do you want to prune them? Have they gotten too big or just have an awkward branch or two? Neither azaleas nor rhododendrons really need to be pruned the way a privet, Rose of Sharon, or mock orange need to be. If you need to do a massive pruning, maybe they're just in the wrong place, and you'd probably be better off moving them; they will usually come back from a vicious pruning, but not always, and in any event it will take a while before they look anything but scalped.

Joan