The Grails Console Plugin is enabled in development environment by default. You can configure running with console plugin in production in you mc-config.groovy file by adding following line:
grails.plugin.console.enabled=true
The console is available at <mc–url>/console and by default is restricted to ADMIN role only.
The drawback of console is that it doesn't provide updates during the execution - the result printed using println or out << 'text' is shown after the whole task is finished. The simples way how to get feedback is to use the log.error 'text' call which will be appended to system log. I haven't found yet the proper setting to enable logging for console in lower log levels but error level is printed every time.