Softices docs show the line and where it is that starts softice.
I used older v 3.63 and I used to just comment out the startup line and reboot the computer. When softice is needed, just take the comments off
and reboot again. It isn't elegant, but it will let you have softice on your computer without it running all of the time. The line used to be in the autoexe.bat file on my old win98se I think.
Regards