The only way to get CF8, now (AFAIK) is to contact Adobe sales and ask if they have a link that will go to CF8 without redirecting to CF10.
The version of CF doesn't matter as far as local/production development - they all can be set for either.
Not sure if just copying the CFIDE folder will fix whatever issue you're having. Likely you'll have to reinstall from scratch.
I just sent a private msg to you, kindly let me know the Operating system.
This is on Windows 2003 Server 32-bit.
I found the original CF8 install file (coldfusion-80-win.exe) and the update to 8.01 (coldfusion-801-win_updater.exe) and used them to install the Developer Edition onto my local PC.
I then zipped up the CFIDE folder and sent it to the server, and extracted it into the correct place (on my server, it was under C:\ColdFusion8\wwwroot)
I had to change the CFIDE path in the \lib\neo-runtime.xml file to get around the "Could not find the ColdFusion Component or Interface CFIDE.adminapi.security" error.
And now it all works again. Thank you for your advice.