The script bellow saves the files attached in a selection of emails into a destination folder. you can then use these files to add them in Address Book.
set Dest to ((path to desktop folder) as string) & "FMail:" -- the folder to save attached files
tell application "Mail"
activate
set ListMessage to selection -- take all emails selected
repeat with aMessage in ListMessage -- loop through each message
set AList to every mail attachment of aMessage
repeat with aFile in AList --loop through each files attached to an email
if (downloaded of aFile) then -- check if file is already downloaded
set Filepath to Dest & (name of aFile)
save aFile in Filepath as native format
end if
end repeat -- next file
end repeat -- next message
end tell
I added many comments to make it clear. then you will be able to adapt it to your needs.