Dear Amit,
See we are using Pidgin only for Gtalk here. For yahoo,
there is another way to connect. Yahoo has an old version of their
messenger available for red hat 9, and that is what we use. You can try
downloading the same rpm. (If on a debian system, use alien to install)
That works great via the proxy. For irc, I use online CGI proxies :)
Regards,
Karthik