sorry if somebody already mentioned, however use bill's envsphere with smart IBL method, in which parametric location of sun on equirectangular hdri in (u,v) co-ords is used to position sun (poser inf lite) to correspond to sun location on associated hdri, using simple cartesian/polar co-ordinate conversion math.  see hdrlabs.com for explanation of sIBL method.

in addition, OP is advised to quit using IBL/AO until somebody explains how to use that (poser 7 and earlier).