Take her to a swingers club. Tell her there is no pressure you are just going to watch - for curiosity's sake. Try to get her to dress provocatively - but this is secondary. Feed her her favorite alcoholic drink - the stronger, the better. Eventually some guy will come to your booth and introduce himself. He may even talk for a while. Eventually he will ask your drunk wife to dance. This is how you start. Once she makes contact there is a good chance she will enjoy herself and you have broken the ice. DONT expect her to have sex the first time. In fact, heavy petting might be a maximum first goal. Good luck. This will work.
I think you are on the right track here. If she was raised conservatively, it might be best to ease her in. If she likes to drink, that can lower her inhibitions and let her real self out.