If you are looking for a way to copy a file / DLL from the GAC, here is your answer:
http://www.tipscentre.net/Details/Copy-DLL-From-GAC-Assembly.aspx

Click Start then click RUN.
Type “C:\windows\assembly\gac” and then press enter key.
GAC folder will be opened.
Go one step up by clicking the “UP” icon in the standard button toolbar.
Then search for your required dll file.
If you find the required dll then just copy it.
Enjoy!