Ability to set MAVEN_OPTS for Maven2 build definitions

It would be useful if build definitions for Maven2 projects had a parameter for setting the MAVEN_OPTS environment variable.

The specific case that I'm encountering is one of my build definitions needs to have -Xmx set so that it will have enough memory.
The only suggestions I could find online for this was to set MAVEN_OPTS when starting up continuum.
I have done this, and it works; but I would prefer it if I could set this on a case by case basis for the build definitions, because only this one build needs the extra heap space.