Is it possible to configure pinger from the manager? we're trying not to enable terminal access to the box and have outside support modify and enhance splunk via the web app. Can Pinger be configured via the manager or the web in another manner?
No, you cannot do this in the manager.... But, since the Pinger app uses one single config file, this file could be modified by any tool which is able to do so.
For example, you could modify the file outside of Splunk and use puppet to deploy it. Another example would be to setup some fancy Web editor tool where you can modify the file directly in a web browser.
Basically there are almost endless ways to do this kind of file modification, outside of Splunk though.
Providing such a way of changing a .conf file is also a security risk and remember that typos happen fast. In the end it all comes to a point where you have to judge the benefits against the risks of any solution, that will allow 'remote' modification of any .conf file.