Quote - However, I've tried creating a Poser.exe file (just like Superman said) and placed it in my Smith Micro/Poser Pro directory.

You almost certainly have extensions hidden (this is the Windows default), so your file is really called Poser.exe.txt

 

Quote - I don't know why, but I don't see a DAZ directory so I can't install it there.

When you run the installer, instead of selecting "Poser" as the install type, select "DAZ Studio", then when it ask for the destination just choose the Poser Runtime where you want to install.
Doing this is the easiest way to get round the check for Poser.exe (exactly the same files are installed AFAIK).