If your slave cylinder is leaking, then yes, tranny removal is the only way. If you are not handy under the hood, I don't sugest you try it. It's not something you want to take on in your driveway. And if you've ever worked on a hyd clutch before...forget what you know.
Ford over engineered this one. Hopefully I've talked you out of doing it yourself.
A good shop will probably charge you in the relm of $500.00-$600.00. Starting to think about doing yourself again aren't you? Don't do it, unless you have a couple of guys to help you, level ground, and full reserve of cuss words.
every penny of that job.