You should consider setting the "mailcap-search-path" and "mimetype-search-path" pine config variables, and specifying a home rolled "viewer" that saves the files the way you want on your server. That way all you have to do is hit "V" to "view" each attachment, and it will automaticly be saved the way you want it.

For more info...

• http://www.washington.edu/pine/faq/config.html#9.11
• http://www.math.washington.edu/~chappa/pine/pine-info/misc/mime.html