Actually, it's no problem. Get yourself a crow's foot in the correct size. Then you will need to use extensions to get down there. And you will probably only be able to move it about 1/3 of a turn each time. But really no problem.
Hit it with PB Blaster. Work on it when cool - like after sitting overnight (so the header bung is not hot/expanded - also so you dont get burnt). When you remove the EGR end, make sure you are loosening - it's upsidedown. If it's really bad, you might need a breaker bar to get the nuts started, but I doubt that will be necessary.
Get your replacement part from 50Resto for about $50 under their exhaust/accessories category (or anywhere else you can find). It's more like $100 from the dealer.
If you have to wait for the part, you could get some caps. Home Depot has something that will fit. Or you could just put a penny under the old fitting to cap it off. Someone said you can melt the penny and have it drop into your cats and screw those up if you do that, but I ran mine all summer w/o issue like that. (BTW, depending on the leak, you may be able to patch it with that exhaust patch tape.)
Good luck.