How would you add Pecans to the calculation?

I found a recipe thr a Pecan Pie Barleywine that uses 12 oz of crushed roasted pecans to the mash and then 6 oz more to the boil.  How do you add this the beersmith 2.0.  I figure it will provide some sort of IBU but not sure.  Please help.

I would just create a misc ingredient for pecans.  Then add your 12 oz to the mash, and 6 oz to the boil. 

I wouldn't expect any IBUs...tannins is more likely.  I'd make darn sure there is no SHELL in the pecans before you add them.  Pecan shell is crazy full of tannins and HARSH bitterness.