Hi Wolfgang, Thanks for the question. I am also using PyCharm on Windows 7 and I have had no issue with accessing the PCI libraries by default. I get all of the expected results, such as auto complete functions/classes, list arguments, etc.
However, I do know that you can setup virtual environments in PyCharm by going to File --> Settings then in the Settings panel, select Project (the active project) in the navigation pane. Then click on the config button next to the interpreter list and click More... in the pop up panel, select the correct interpreter and click on the bottom button on the right (env list). Add all of your environment paths to that list that you need. for PCI's library, go to the exe folder for your Geomatica install (one level above pci folder). In windows it is C:\PCI Geomatics\Geomatica 2014\exe
Good luck and happy coding!