To reference a general configuration file or template:
[Templates] Configs = %OMSYSHOME%\path\to\sometemplate.ini
Your DITA2Go distribution includes configuration templates already chained together through references like this; see §39.1.3 Understanding how templates are chained together.
When DITA2Go creates a starting configuration file for a new project, that file includes the first link in the chain. For example, a starting project configuration file for Word output includes this reference:
[Templates] Configs = %OMSYSHOME%\d2g\local\config\local_d2rtf_config.ini
If you want to insert another configuration file (for example, myspecial.ini) in the chain between the project configuration file and local_d2rtf_config.ini, you would copy this reference into myspecial.ini, and replace it with the following reference in the project configuration file:
[Templates] Configs = path\to\myspecial.ini
You can chain configuration files together by including in each a [Templates]Configs setting that references yet another template or configuration file. You can have as many referenced files chained as you please; each overrides the one it references, and all others that precede the referenced template in the chain. The most specific configuration rules. See §39.5 Creating your own configuration templates.
Settings that specify paths to configuration templates, or to any other files in the DITA2Go distribution directory structure, should use absolute paths that begin with environment variable %OMSYSHOME%; for example:
Configs = %omsyshome%\d2g\local\config\local_d2htm_config.ini
If you specify a relative path for any setting in configuration section [Templates], that path is considered to be relative to the configuration file in which the setting occurs.
If the same setting has different values in a referenced template or configuration file and in a file that references that template, the value in the referencing file takes precedence, allowing you to override the template when necessary:
See §42.1.2 Understanding precedence of configuration settings.