That is not a task for deployment stage; that is post-deployment configuration, which is also covered on that page..
I'd say that preferred would be using ADMX in Windows AD domains; however, using .xcd files is, of course, also possible. One would need to backup one's registrymodifications.xcu, then toggle OpenGL and exit LO, then diff the updated registrymodifications.xcu with its backup to find the relevant setting, which would be in this case
<item oor:path="/org.openoffice.Office.Common/VCL"><prop oor:name="UseOpenGL" oor:op="fuse"><value>false</value></prop></item>
... and then create own .xcd like
<?xml version="1.0"?>
<oor:data xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:oor="http://openoffice.org/2001/registry">
<dependency file="main" />
<oor:component-data xmlns:install="http://openoffice.org/2004/installation" oor:name="Common" oor:package="org.openoffice.Office">
<node oor:name="VCL">
<prop oor:name="UseOpenGL" oor:op="fuse" oor:type="xs:boolean">
<value>false</value>
</prop>
</node>
</oor:component-data>
</oor:data>
... which you put into C:\Program Files\share\registry on user boxes.
