i don't think this will be possible without modifing super pi.exe itself which is not allowed of course.
the "original" super pi (without the decimal digits) can be used, but you always have to enter your result with xx.999 seconds.
so if you get, for example, 25 seconds on a run with the orignal super pi you have to enter 25.999 when submitting the result, because you can't tell if your result is 25 seconds flat or 25.999.