Looks like their ESB, yeah?
From that, it seems they go from about 1.058 to 1.014.
I would go 50% MO and 50% pale on the main bill, and do like 1 pound of 60L for the color and some flavor (fairly typical crystal used in ESB recipes. Depending on how dark you want it, maybe up it to 80L)
You can just figure out the bittering level of Challengers at 60, and then finish with the challenger and ekgs at 15. I'd do 1/2 oz. each at 15 minutes.
As for the dry hop, I'd probably use about 2 ounces total. You could split it into .5 each, or you could blend a bit differently.
I haven't seen an exact clone for this online, so you just have to wing it. plug it all into beersmith or whatever program you want to hit your numbers.