To install on Fedora (and possibly others) simply grab the .deb file Dossy kindly published here. Open the .deb in archive manager. Open the contained data.tar.gz file. Then drop the contained “convcharcount.la” and “convcharcount.so” files into your /usr/lib/pidgin/ directory. You’ll need to do this as root.
Now open Pidgin (restart is not required), Tools > Plugins, and tick the conv. input character count plugin. Bingo, it works like a charm for me on Fedora 8 with Pidgin 2.4.1. Thanks Dossy. 🙂