It should work fine in 6.5.x with small changes, but if you're thinking of using this mod you should know that I've updated it a bit. The biggest change is that now it only asks for a security code after 2 failed login attempts in a row. I also fixed some browser-specific bugs so I recommend you use this new version instead of the one above. Please download captchamod.zip attached to the first post in this thread, but then follow the instructions attached to this reply. Let me know if you have any problems.
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