First, welcome to Stangnet!
I checked, wow, they want ~$60 for a new egr pipe (
1994-95 Mustang 5.0L Egr To Header Tube by Ford at LRS - Same Day Shipping!) . You could likely get one much cheaper at a local junk yard of they have one.
Otherwise, using JB Weld or steel epoxy putty is one thing that I can think of. My guess is that welding the hole (if you could) would be a waste.
For steel epoxy putty info, see:
http://www.stangnet.com/mustang-forums/801471-lower-radiator-support-suggestions.html#post8071268
http://www.stangnet.com/mustang-forums/683385-cant-find-doors-need-help.html#post6692156
Either way,
prep will be the important thing. Sandpaper the whole area until you're down to clean new metal. Clean the area with Acetone (nail polish remover often also works), or as a last resort, clean water.
You have to circle the whole area with either JB Weld or the epoxy putty. If you get the epoxy putty from Home Depot, you'll have plenty to cover a wide area.
Just so you know, you're looking at spending at least $5 -> $10 (my guess is ~$10) to fix the pipe. It's a that
may last a few years.
IMHO, your best bet is to go to the classifieds and do a "Want To Buy" post like: "WTB: 94-95 EGR Tube".
SN95 Mustangs - SN95 Mustang WTB/Trade Cars & Parts at StangNet
BTW: A friendly reminder to people, send a PM (Private Message) if you have one to sell and want to contact the OP.
NO selling in tech!
Good Luck!