Override module config from defines?

[blueyed]

Is it possible to override config from the module itself in your site.pp?

I have tried e.g. Munin::Plugin[postfix_mailvolume] { ensure => present } but without success ("Only subclasses can override parameters").

I have now changed the module itself, but it would be nice to do so without touching the module's source.

If this is possible somehow, please also document it in the README.