The Collaborative International Dictionary of English v.0.48:
Iniquitously \In*iq"ui*tous*ly\, adv. In an iniquitous manner; unjustly; wickedly. [1913 Webster]WordNet (r) 3.0 (2006):
iniquitously adv 1: in an iniquitous manner; "they really believed that the treaty of Versailles was iniquitously injust"