Assuming you have a source to copy from that does accept Ctrl-C to copy, that'd be a method for getting data into the clipboard.
Typing out text is specifically what the "Quick Input" action is for.
You can combine that with the appropriate token to retrieve the copied text from the clipboard (see the "Text (and Text-To-Speech) Tokens" section of VoiceAttackHelp.pdf, which can be opened by pressing F1 while VoiceAttack has focus)