virtual servers with iis

hi, i want to have two webroots with a diffrent configuration (php.ini) on the same physical server. starting php.exe with "-c \secondconfig" works fine from the console but is ignored when php.exe is spawnd by iis. my second attempt was to start php.exe through a second program that only does a CreateProcess() setting another working directory but now all umlauts accessed from a db (and only them !) are corupptet. any advices ? harald