Check out the following threads for instructions on how to add a malt to your ingredients list and specifically midnight wheat.
http://www.beersmith.com/forum/index.php/topic,16806.msg63434.html#msg63434
http://www.beersmith.com/forum/index.php/topic,8511.msg34466.html#msg34466
Additionally, TheBishop has uploaded an updated listing of Breiss malts and extracts which can be found at http://www.beersmith.com/forum/index.php/topic,20468.0.html