1) "acquire" a copy of Photoshop 7 first or "borrow it from a friend who has it"
2) click setup.exe or install.exe or soemthing to that effect
3) keep clicking next until you get to the part where you need to enter a cd key, enter the CD key if you have it, if not, sucks to be you :P
4) keep clicking next and it will install
tips: it is better if you install Photoshop cleanly, since I think it installs seperately from PS6 anyways.