All version of CookieSwap are available for download from the Firefox Add-On Site

COOKIESWAP_0.5.273 (Supports Firefox 4 - Firefox 6!)
This is the latest version of CookieSwap that has support for the latest Firefox versions.  It is functionally identical to 0.5.253 below.
It's also available directly from the FIrefox Add-On Site.
 
COOKIESWAP_0.5.253 (Supports Firefox 3 and earlier)
Also available directly from the Firefox Add-On Site.