Easyapache installs the older 2.X release of Xcache. It's better to install 3.0.1 direct via command line
# wget
http://xcache.lighttpd.net/pub/Releases/3.0.1/xcache-3.0.1.tar.gz
# tar -xzvf xcache-3.0.1.tar.gz
# cd xcache-3.0.1
# phpize --clean && phpize
# ./configure --enable-xcache
# make
# make install
and then add extension=xcache.so and your xcache settings to php.ini and reload apache