I don't understand what you're asking. The terminology you're using is bizarre. A signature does not apply to a machine. It applies to a document. You can freely copy a signed document (signed PDF, for instance) from one machine to another. You cannot paste anything into a PC. You can copy and paste a file to a folder on a hard drive on a PC.
If this does not answer your question, describe as detailed as you possibly can what is it that you want to achieve.
Search your system for a file named "appearances.acrodata".
On my Win7/Acrobat9 system, it's in: C:\Users\[username]\AppData\Roaming\Adobe\Acrobat\9.0\Security