The ODT exporter can work with popular converters with little or no extra configuration from your side. See Extending ODT export. If you are using a converter that is not supported by default or if you would like to tweak the default converter settings, proceed as below.
Name your converter and add it to the list of known converters by customizing
org-export-odt-convert-processes. Also specify how the
converter can be invoked via command-line to effect the conversion.
Specify the set of formats the converter can handle by customizing the
org-export-odt-convert-capabilities. Use the default value
for this variable as a guide for configuring your converter. As suggested by
the default setting, you can specify the full set of formats supported by the
converter and not limit yourself to specifying formats that are related to
just the OpenDocument Text format.
Select the newly added converter as the preferred one by customizing the