Your manifold is aluminum. The coolant hole that the EGR cooler mates to is 1". The pipe that you use is 1" tube 3000 series or 6061 which are easily acquired from a metal dealer. 0.0625 (1/16") wall is fine. You can even get one pre-moulded (90 degrees) if you search hard enough on the net. You will then need to reduce it to 3/4" for teh hose fitting to the Oil cooler fitting. The other hole (air hole) will need to be welded shut. Use a 1/8" piece cut to fit and weld it shut. You can do the same for the top or just leave the EGR valve in it. Use 4043 wire/filler. Tig is the only way to go, although you could mig certain portions.
Now I would suggest since you asked how to do it, you probably do not have the skill set to do this correctly yourself. Check out this post for photos of what I did.
EGR Removal Pics
FCDP makes a kit similar to my work that is crafted very well. You can buy an intake manifold on ebay reasonably priced, have it modified and then the swap out would only take a few hours to do. Otherwise you may be waiting for the intake manifold, if you want yours back.