dunno about elements but in PS you create multiple layers, lifting the exposure on the upper ones past the original and dropping it on the ones below and then process them then flatten them
if it wont let you do that then just make 3 copies of the photo, one original, one where youve dropped the exposure and another where youve lifted it. Then download a free program such as photomatix pro (or something similar) and drag them into it to process them for you