Building

# yum install gcc libpurple-devel glib2-devel

Enabling

Enable the plugin via Tools -> Plugins (Ctrl-U). Set password in Edit Account "Password:" field. Then check "enable userserv auth" in Edit Account -> Advanced.

SELinux

chcon -t textrel_shlib_t ~/.purple/plugins/userserv.so

sudo semanage fcontext -a -t textrel_shlib_t ~/.purple/plugins/userserv.so