Tim Cole has been hassling me to do this for 12 months. Today he found me in a receptive, VB mode, so here it is.
Paste as Text Only (Windows zip downloadable)
Just download, unzip and place the .exe into your InDesign 2.0 Scripts folder.
Instead of using Edit>Paste, select the insertion point or textframe you wish to paste into, and using the Windows>Scripts palette, double click on this script. It will then paste as text only — no formatting, into relevant item.
For MacOS users, Tim has a MacOS version here: Paste as Text Only (MacOS .sit from adobeevangelists.com).