At the end of this post ...
gesuchte title aus TCM einfachst nach MP3Tag übergeben
... I have made a rather similar proposal for using path entries from the Clipboard.
A simple general usage of [Ctrl]+[V] from within Mp3tag, as you have described, seems not so easy to be realized, because Mp3tag has its own Clipboard functionalities, which are controlled by the known Clipboard shortcut keys.
DD.20110420.1022.CEST