1 - Run apsCS4.exe and choose where you want to extract the file.
2 - Go to where the file is extracted and run Setup.exe to install.
3 - After installation, go to your folder Photoshop CS3.
Usually "C: \ Program Files \ Adobe \ Adobe Photoshop CS3" as default.
4 - Copy the folder "ATM" for the directory CS4 installation and overwrite all. "C: \ Program Files \ Adobe \ Adobe Photoshop CS4" Usually "C: \ Program Files \ Adobe \ Adobe Photoshop CS4"
5 - Use the keygen to get a serial, then select Other Activation Opion.
Select activate by phone and put in the request for the number of Keygen to get an activation number.