Below is the tutorial on how-to install DOM-XML in DirectAdmin using customapache.

# yum install libxml2-devel libxslt-devel libgcrypt-devel
# cd /usr/local/directadmin/customapache
# vi configure.php

Add this to configure.php before –with-gd \ :
–with-dom=/usr/lib \
–with-dom-exslt=/usr/lib \
–with-dom-xslt=/usr/lib \

# ./build clean
# ./build php n
# service httpd restart