And here's an extract recipe I found.
I haven't brewed this, and I haven't tried Black Butte Porter, so I don't know how close this would be to the real thing:
6 lbs Light DME
6 oz chocolate malt
6 oz black patent malt
8 oz honey malt
8 oz crystal 10L
4 oz toasted barley (toast at 350F for 10 minutes)
8 oz maltodextrin
1.5 oz Galena 13%AA (60 min)
1 oz Cascade 5.5%AA (30 min)
1 oz Tettnanger 4.5%AA (5 min)
Wyeast 1338 European Ale yeast
Steep grains in a grain bag for 30 min in 1.5 gallons of water at 158F.
Sparge with 2 quarts of water at 170F.
Mix in extract and maltodextrin and top off with water to desired optimum level for your brew pot. Bring to a boil and follow hops schedule.
Looks reasonable I guess, but I don't know that just steeping honey malt and toasted barley would do you much good. I'd probably do a partial mash instead of steeping (thanks to EdWort's Haus Pale Ale thread for the procedure):
Heat 2.5 qts of water to 168F in a pot.
Heat 3 qts of water to 170F in another pot.
Add (2 lbs total) crushed grains to the pot with the 168F water and stir very throughly.
Put lid on that pot, placed in oven at 150F.
Let it sit for an hour.
Pour the wort into your brew pot through a strainer. Put grains back into pot.
Pour the 170F water into the pot where your grain is, stir throughly, let sit for 10 mins. Pour that wort into your brew pot through your strainer.
Bring to a boil, add extract and maltodextrin, follow hops schedule.
I'd probably be inclined to try the recipe desertbronze posted first, but anyway, here's an alternative.