The planning of the ISOPHOT (Lemke et al. 1996) calibration during the Performance Verification (PV) phase, with its 4 day turn-around cycle, required mission planning tools in the hands of the Instrument Dedicated Team (IDT). We developed a system, that gave full command of all instrument functions and which allowed planning of the observations for entire 16 h revolutions with an accuracy of seconds. Thus, time consuming loops between the IDT and Mission Planning were avoided and a maximum scheduling efficiency was achieved. Only in this way were raster observations of Solar System Objects possible, which were an important ingredient for the photometric calibration. Access to all functions of the instrument was mandatory, to measure in unusual instrument configurations, and to test updates of Astronomical Observation Templates (AOT). The heterogeneous system was built in very short time and consisted of a variety of components like spreadsheets, unix shell scripts, and programs written in IDL and FORTRAN. These were running on various platforms under VAX-VMS, Ultrix, Solaris and Microsoft Windows 3.11. We will describe the system and its performance and discuss in retrospect advantages and disadvantages introduced by the approach.