Welcome to the community! I've moved your question to the PADS sub-community where it will be picked up by more PADS users. You might also check out the links on http://supportnet.mentor.com/reference/other-info/Earlier-Version-PADS.cfm. Some of them might help.
You use the Library Converter to update older libraries to V9 format. The converter will convert .pt4 and .pt07 format libraries to .pt9 format.
If you have support we have a video that explains the converter at:
The converter file is named libconv9.exe and can be found at:
Perfect. Thanks for your help!