** I was wondering if anyone has had this done and could tell us the work involved and the approximate cost to hire contractors to do this for us??? **
I think that would be a lot to ask without being able to see what the situation is in your home, what exactly would be required and without knowing what professionals charge in whatever area you happen to live in. You'll likely need to call someone in to provide you a realistic estimate.
You can find some *general* considerations about the washer/dryer installation at the following link.