Hi,
first of all, there is no Custom way to install the plugin by putting a file somewhere manually; the RTAS version needs to be in a specific place and the installer puts it there.
I am assuming you have moved the VST dll file in the Pro Tools DAE/Plug-Ins folder, which is not good, it breaks the Standalone functionality.
Since PT 8 and RTAS is 32-bit, you need to run the 32-bit installer.
You also need to be on Pro Tools 8.0.5 or higher and Insert the EZdrummer 2 plugin on a Stereo Instrument Track.