If you would like to enter the U.S. as a B2 nonimmigrant, but face one or several grounds of in admissibilty, there is a discretionary waiver available under INA 212(d)(3)(A).
You apply for the waiver on Form I-192, which can be found and downloaded on the USCIS website. http://www.uscis.gov/portal/site/uscis/menuitem.5af9bb95919f35e66f614176543f6d1a/?vgnextoid=68db2c1a6855d010VgnVCM10000048f3d6a1RCRD&vgnextchannel=db029c7755cb9010VgnVCM10000045f3d6a1RCRD.