|Did you try pasting the text as Text?|
Depending on what version you are running, it might be:
Right Click...Paste Options...Text
For what it's worth, I just selected a bunch of text from an Excel document and pasted it into Word with a simple Ctrl-V. In both cases, the text was fully editable.
I did this both within 2003 and 2010 independently and then across versions and had no problem editing the text after it was pasted into Word.
It could be something with your source data that is preventing it from being edited.
Click Here Before Posting Data or VBA Code ---> How To Post Data or Code.