It doesn't need to be in the main poser directory. You can point the installer where you want but it will only install if it see's a poser.exe file there. Again, this doesn't need to be a copy of the actual .exe, you can create an empty text file if you wish and rename it to poser.exe

The runtime/libraries/!DAZ directory needs to be in the main install path though otherwise things take a long time to load. You can simply copy the directory there and rename the original or remove it.